wireshark/epan/dissectors/packet-q931.c

/* packet-q931.c
 * Routines for Q.931 frame disassembly
 * Guy Harris <guy@alum.mit.edu>
 *
 * Modified by Andreas Sikkema for possible use with H.323
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include "config.h"

#include <epan/packet.h>
#include <epan/tap.h>
#include <epan/nlpid.h>
#include "packet-q931.h"
#include "packet-e164.h"
#include <epan/prefs.h>
#include <epan/expert.h>
#include <epan/reassemble.h>
#include <epan/sctpppids.h>
#include <epan/lapd_sapi.h>
#include "packet-tpkt.h"


/* Q.931 references:
 *
 * http://www.acacia-net.com/Clarinet/Protocol/q9313svn.htm
 * http://www.acacia-net.com/Clarinet/Protocol/q9311sc3.htm
 * http://www.acacia-net.com/Clarinet/Protocol/q9317oz7.htm
 * http://www.protocols.com/pbook/isdn.htm
 * http://freesoft.org/CIE/Topics/126.htm
 * http://noc.comstar.ru/miscdocs/ascend-faq-cause-codes.html
 * http://www.andrews-arnold.co.uk/isdn/q931cause.html
 * http://www.tulatelecom.ru/staff/german/DSSHelp/MessList/InfEl/InfElList.html
 */

void proto_register_q931(void);
void proto_reg_handoff_q931(void);

static void reset_q931_packet_info(q931_packet_info *pi);
static gboolean have_valid_q931_pi=FALSE;
static q931_packet_info *q931_pi = NULL;
static int q931_tap = -1;

static dissector_handle_t q931_handle;
static dissector_handle_t q931_over_ip_handle;

static int proto_q931                                   = -1;
static int hf_q931_discriminator                        = -1;
static int hf_q931_coding_standard                      = -1;
static int hf_q931_interpretation                       = -1;
static int hf_q931_pres_meth_prot_prof                  = -1;
static int hf_q931_high_layer_characteristics           = -1;
static int hf_q931_extended_high_layer_characteristics  = -1;
static int hf_q931_extended_audiovisual_characteristics = -1;
static int hf_q931_information_transfer_capability      = -1;
static int hf_q931_transfer_mode                        = -1;
static int hf_q931_information_transfer_rate            = -1;
static int hf_q931_layer_ident                          = -1;
static int hf_q931_uil1                                 = -1;
static int hf_q931_call_ref_len                         = -1;
static int hf_q931_call_ref_flag                        = -1;
static int hf_q931_call_ref                             = -1;
static int hf_q931_message_type                         = -1;
static int hf_q931_maintenance_message_type             = -1;
static int hf_q931_segment_type                         = -1;
static int hf_q931_cause_location                       = -1;
static int hf_q931_cause_value                          = -1;
static int hf_q931_number_type                          = -1;
static int hf_q931_numbering_plan                       = -1;
static int hf_q931_extension_ind                        = -1;
static int hf_q931_extension_ind_preference             = -1;
static int hf_q931_extension_ind_new_status             = -1;
static int hf_q931_calling_party_number                 = -1;
static int hf_q931_called_party_number                  = -1;
static int hf_q931_connected_number                     = -1;
static int hf_q931_redirecting_number                   = -1;
static int hf_q931_screening_ind                        = -1;
static int hf_q931_presentation_ind                     = -1;

/* fields for Channel Indentification IE */
static int hf_q931_channel_interface_explicit           = -1;
static int hf_q931_channel_interface_type               = -1;
static int hf_q931_channel_exclusive                    = -1;
static int hf_q931_channel_dchan                        = -1;
static int hf_q931_channel_selection_bri                = -1;
static int hf_q931_channel_selection_pri                = -1;
static int hf_q931_channel_map                          = -1;
static int hf_q931_channel_element_type                 = -1;
static int hf_q931_channel_number                       = -1;


static int hf_q931_segments = -1;
static int hf_q931_segment = -1;
static int hf_q931_segment_overlap = -1;
static int hf_q931_segment_overlap_conflict = -1;
static int hf_q931_segment_multiple_tails = -1;
static int hf_q931_segment_too_long_segment = -1;
static int hf_q931_segment_error = -1;
static int hf_q931_segment_count = -1;
static int hf_q931_reassembled_in = -1;
static int hf_q931_reassembled_length = -1;

/* Generated from convert_proto_tree_add_text.pl */
static int hf_q931_user_information_bytes = -1;
static int hf_q931_restart_indicator = -1;
static int hf_q931_call_state_data = -1;
static int hf_q931_first_segment = -1;
static int hf_q931_packet_size_backward_value = -1;
static int hf_q931_packet_size_forward_value = -1;
static int hf_q931_information_rate_minimum_outgoing = -1;
static int hf_q931_bearer_capability_data = -1;
static int hf_q931_uil2_info = -1;
static int hf_q931_netid_facility_specification = -1;
static int hf_q931_bearer_capability_stop_bits = -1;
static int hf_q931_netid_length = -1;
static int hf_q931_channel_data = -1;
static int hf_q931_call_state = -1;
static int hf_q931_party_subaddr_type = -1;
static int hf_q931_uil3 = -1;
static int hf_q931_user_information_str = -1;
static int hf_q931_bearer_capability_user_rate = -1;
static int hf_q931_channel_slot_map = -1;
static int hf_q931_bearer_capability_modem_type = -1;
static int hf_q931_cause_data = -1;
static int hf_q931_cause_recommendation = -1;
static int hf_q931_bearer_capability_parity = -1;
static int hf_q931_cause_call_rejection_reason = -1;
static int hf_q931_party_category = -1;
static int hf_q931_progress_indicator_location = -1;
static int hf_q931_bearer_capability_packet_window_size = -1;
static int hf_q931_extension_reason = -1;
static int hf_q931_information_rate_minimum_incoming = -1;
static int hf_q931_user_protocol_discriminator = -1;
static int hf_q931_uil2 = -1;
static int hf_q931_progress_indicator_description = -1;
static int hf_q931_bearer_capability_mode = -1;
static int hf_q931_not_first_segment = -1;
static int hf_q931_fast_select = -1;
static int hf_q931_netid_plan = -1;
static int hf_q931_cause_call_message_type = -1;
static int hf_q931_reverse_charging_ind = -1;
static int hf_q931_high_layer_compat_data = -1;
static int hf_q931_progress_indicator_data = -1;
static int hf_q931_pl_window_size_forward_value = -1;
static int hf_q931_cause_call_rec_timer = -1;
static int hf_q931_bearer_capability_window_size = -1;
static int hf_q931_cause_call_user_specific_diagnostic = -1;
static int hf_q931_channel_interface_id = -1;
static int hf_q931_uil3_additional = -1;
static int hf_q931_party_subaddr = -1;
static int hf_q931_bearer_capability_rate_multiplier = -1;
static int hf_q931_bearer_capability_data_bits = -1;
static int hf_q931_cug_index_code = -1;
static int hf_q931_bearer_capability_default_packet_size = -1;
static int hf_q931_notification_description = -1;
static int hf_q931_information_rate_outgoing = -1;
static int hf_q931_user_information_len = -1;
static int hf_q931_pl_window_size_backward_value = -1;
static int hf_q931_repeat_indicator = -1;
static int hf_q931_cause_call_diagnostic = -1;
static int hf_q931_netid = -1;
static int hf_q931_cause_call_condition = -1;
static int hf_q931_signal = -1;
static int hf_q931_congestion_level = -1;
static int hf_q931_bearer_capability_intermediate_rate = -1;
static int hf_q931_netid_type = -1;
static int hf_q931_information_rate_incoming = -1;
static int hf_q931_party_subaddr_odd_even_indicator = -1;
static int hf_q931_cug_indication = -1;
static int hf_q931_multiple_frame_establishment = -1;
static int hf_q931_message_originator = -1;
static int hf_q931_out_band_negotiation = -1;
static int hf_q931_negotiation_is_done = -1;
static int hf_q931_layer_1 = -1;
static int hf_q931_accept_data_flow_control = -1;
static int hf_q931_mode_of_operation = -1;
static int hf_q931_extension_condition_type = -1;
static int hf_q931_pl_binary_confirmation = -1;
static int hf_q931_pl_request = -1;
static int hf_q931_pl_modulus = -1;
static int hf_q931_network_service = -1;
static int hf_q931_extension_condition = -1;
static int hf_q931_rate_adaption_header = -1;
static int hf_q931_send_data_net_independent_clock = -1;
static int hf_q931_bearer_capability_duplex = -1;
static int hf_q931_accept_data_net_independent_clock = -1;
static int hf_q931_send_data_flow_control = -1;
static int hf_q931_data = -1;
static int hf_q931_layer_1_in_band_negotiation = -1;
static int hf_q931_information_element = -1;
static int hf_q931_information_element_len = -1;
static int hf_q931_date_time = -1;
static int hf_q931_more_data = -1;
static int hf_q931_sending_complete = -1;
static int hf_q931_message_segment = -1;
static int hf_q931_missing_info_element = -1;
static int hf_q931_insufficient_info_element = -1;
static int hf_q931_cumulative_transit_delay = -1;
static int hf_q931_requested_end_to_end_transit_delay = -1;
static int hf_q931_maximum_end_to_end_transit_delay = -1;
static int hf_q931_transit_delay = -1;
static int hf_q931_display_information = -1;
static int hf_q931_keypad_facility = -1;
static int hf_q931_avaya_display = -1;
static int hf_q931_locking_codeset = -1;
static int hf_q931_protocol_negotiation = -1;


static gint ett_q931                    = -1;
#define NUM_IE  256
static gint ett_q931_ie[NUM_IE];

static gint ett_q931_segments = -1;
static gint ett_q931_segment = -1;

static expert_field ei_q931_invalid_length = EI_INIT;
static expert_field ei_q931_date_time = EI_INIT;
static expert_field ei_q931_information_element = EI_INIT;
static expert_field ei_q931_incomplete_ie = EI_INIT;

static const fragment_items q931_frag_items = {
    &ett_q931_segment,
    &ett_q931_segments,

    &hf_q931_segments,
    &hf_q931_segment,
    &hf_q931_segment_overlap,
    &hf_q931_segment_overlap_conflict,
    &hf_q931_segment_multiple_tails,
    &hf_q931_segment_too_long_segment,
    &hf_q931_segment_error,
    &hf_q931_segment_count,
    &hf_q931_reassembled_in,
    &hf_q931_reassembled_length,
    /* Reassembled data field */
    NULL,
    "segments"
};

/* Table for reassembly of fragments. */
static reassembly_table q931_reassembly_table;

/* Preferences */
static gboolean q931_reassembly = TRUE;
static gboolean g931_iso_iec_cause = FALSE;

static dissector_table_t codeset_dissector_table;
static dissector_table_t ie_dissector_table;

/* desegmentation of Q.931 over TPKT over TCP */
static gboolean q931_desegment = TRUE;

/* Subdissectors */
static dissector_handle_t h225_handle;
static dissector_handle_t q931_tpkt_handle;
static dissector_handle_t q931_tpkt_pdu_handle;
static dissector_handle_t data_handle = NULL;

static heur_dissector_list_t q931_user_heur_subdissector_list;

static void
dissect_q931_IEs(tvbuff_t *tvb, packet_info *pinfo, proto_tree *root_tree,
    proto_tree *q931_tree, gboolean is_over_ip, int offset, int initial_codeset);

const value_string q931_message_type_vals[] = {
/*  0 */    { Q931_ESCAPE,               "ESCAPE" },
/*  1 */    { Q931_ALERTING,             "ALERTING" },
/*  2 */    { Q931_CALL_PROCEEDING,      "CALL PROCEEDING" },
/*  3 */    { Q931_PROGRESS,             "PROGRESS" },
/*  5 */    { Q931_SETUP,                "SETUP" },
/*  6 */    { Q931_GROUIP_SERVICE,       "GROUP SERVICE" },
/*  7 */    { Q931_CONNECT,              "CONNECT" },
/*  8 */    { Q931_RESYNC_REQ,           "RESYNC REQ" },
/*  9 */    { Q931_RESYNC_RESP,          "RESYNC RESP" },
/* 10 */    { Q931_VERSION,              "VERSION" },
/* 11 */    { Q931_GROUIP_SERVICE_ACK,   "GROUP SERVICE ACK" },
/* 13 */    { Q931_SETUP_ACK,            "SETUP ACKNOWLEDGE" },
/* 15 */    { Q931_CONNECT_ACK,          "CONNECT ACKNOWLEDGE" },
/* 32 */    { Q931_USER_INFORMATION,     "USER INFORMATION" },
/* 33 */    { Q931_SUSPEND_REJECT,       "SUSPEND REJECT" },
/* 34 */    { Q931_RESUME_REJECT,        "RESUME REJECT" },
/* 36 */    { Q931_HOLD,                 "HOLD" },
/* 37 */    { Q931_SUSPEND,              "SUSPEND" },
/* 38 */    { Q931_RESUME,               "RESUME" },
/* 40 */    { Q931_HOLD_ACK,             "HOLD_ACKNOWLEDGE" },
/* 45 */    { Q931_SUSPEND_ACK,          "SUSPEND ACKNOWLEDGE" },
/* 46 */    { Q931_RESUME_ACK,           "RESUME ACKNOWLEDGE" },
/* 48 */    { Q931_HOLD_REJECT,          "HOLD_REJECT" },
/* 49 */    { Q931_RETRIEVE,             "RETRIEVE" },
/* 51 */    { Q931_RETRIEVE_ACK,         "RETRIEVE ACKNOWLEDGE" },
/* 55 */    { Q931_RETRIEVE_REJECT,      "RETRIEVE REJECT" },
/* 64 */    { Q931_DETACH,               "DETACH" },
/* 69 */    { Q931_DISCONNECT,           "DISCONNECT" },
/* 70 */    { Q931_RESTART,              "RESTART" },
/* 72 */    { Q931_DETACH_ACKNOWLEDGE,   "DETACH ACKNOWLEDGE" },
/* 77 */    { Q931_RELEASE,              "RELEASE" },
/* 78 */    { Q931_RESTART_ACK,          "RESTART ACKNOWLEDGE" },
/* 90 */    { Q931_RELEASE_COMPLETE,     "RELEASE COMPLETE" },
/* 96 */    { Q931_SEGMENT,              "SEGMENT" },
/* 98 */    { Q931_FACILITY,             "FACILITY" },
/*100 */    { Q931_REGISTER,             "REGISTER" },
/*106 */    { Q931_FACILITY_ACKNOWLEDGE, "FACILITY ACKNOWLEDGE" },
/*110 */    { Q931_NOTIFY,               "NOTIFY" },
/*114 */    { Q931_FACILITY_REJECT,      "FACILITY REJECT" },
/*117 */    { Q931_STATUS_ENQUIRY,       "STATUS ENQUIRY" },
/*121 */    { Q931_CONGESTION_CONTROL,   "CONGESTION CONTROL" },
/*123 */    { Q931_INFORMATION,          "INFORMATION" },
/*125 */    { Q931_STATUS,               "STATUS" },

            { 0,                         NULL }
};
static value_string_ext q931_message_type_vals_ext = VALUE_STRING_EXT_INIT(q931_message_type_vals);

static const value_string dms_message_type_vals[] = {
    { DMS_SERVICE_ACKNOWLEDGE,  "SERVICE ACKNOWLEDGE" },
    { DMS_SERVICE,              "SERVICE" },
    { 0,                        NULL }
};

/*
 * NOTE  For call reference flag (octet 2)
 * Bit8
 *  0 The message is sent from the side that originates the call reference
 *  1 The message is sent to the side that originates the call reference
 */
static const true_false_string tfs_call_ref_flag = {
    "Message sent to originating side",
    "Message sent from originating side"
};

static const true_false_string tfs_interface_type = {
    "Primary rate interface",
    "Basic rate interface"
};

static const true_false_string tfs_channel_exclusive = {
    "Exclusive; only the indicated channel is acceptable",
    "Indicated channel is preferred"
};

static const true_false_string tfs_channel_map = {
    "Channel indicated by slot map",
    "Channel indicated by number"
};

/*
 * Information elements.
 */

/* Shifted codeset values */
#define CS0 0x000
#define CS1 0x100
#define CS2 0x200
#define CS3 0x300
#define CS4 0x400
#define CS5 0x500
#define CS6 0x600
#define CS7 0x700

#define Q931_IE_SO_MASK 0x80    /* single-octet/variable-length mask */
/*
 * Single-octet IEs.
 */
#define Q931_IE_SO_IDENTIFIER_MASK     0xf0    /* IE identifier mask */
#define Q931_IE_SO_IDENTIFIER_SHIFT       4    /* IE identifier shift */
#define Q931_IE_SO_IE_MASK             0x0F    /* IE mask */

#define Q931_IE_SHIFT                  0x90
#define Q931_IE_SHIFT_NON_LOCKING      0x08    /* non-locking shift */
#define Q931_IE_SHIFT_CODESET          0x07    /* codeset */

#define Q931_IE_MORE_DATA_OR_SEND_COMP 0xA0    /* More Data or Sending Complete */
#define Q931_IE_MORE_DATA              0xA0
#define Q931_IE_SENDING_COMPLETE       0xA1

#define Q931_IE_CONGESTION_LEVEL       0xB0
#define Q931_IE_REPEAT_INDICATOR       0xD0

/*
 * Variable-length IEs.
 */
#define Q931_IE_VL_EXTENSION        0x80    /* Extension flag */
/*  extension bit. The bit value "0" indicates that the octet continues through the     */
/*  next octet. The bit value "1" indicates that this octet is the last octet       */

static const true_false_string q931_extension_ind_value = {
    "last octet",
    "information continues through the next octet"
};


/*
 * Codeset 0 (default).
 */
#define Q931_IE_SEGMENTED_MESSAGE        0x00
#define Q931_IE_CHANGE_STATUS            0x01
#define Q931_IE_BEARER_CAPABILITY        0x04
#define Q931_IE_CAUSE                    0x08
#define Q931_IE_CALL_IDENTITY            0x10
#define Q931_IE_CALL_STATE               0x14
#define Q931_IE_CHANNEL_IDENTIFICATION   0x18
#define Q931_IE_FACILITY                 0x1C
#define Q931_IE_PROGRESS_INDICATOR       0x1E
#define Q931_IE_NETWORK_SPECIFIC_FACIL   0x20    /* Network Specific Facilities */
#define Q931_IE_NOTIFICATION_INDICATOR   0x27
#define Q931_IE_DISPLAY                  0x28
#define Q931_IE_DATE_TIME                0x29
#define Q931_IE_KEYPAD_FACILITY          0x2C
#define Q931_IE_INFORMATION_REQUEST      0x32
#define Q931_IE_SIGNAL                   0x34
#define Q931_IE_SWITCHHOOK               0x36
#define Q931_IE_FEATURE_ACTIVATION       0x38
#define Q931_IE_FEATURE_INDICATION       0x39
#define Q931_IE_ENDPOINT_IDENTIFIER      0x3B
#define Q931_IE_SERVICE_PROFILE_ID       0x3A
#define Q931_IE_INFORMATION_RATE         0x40
#define Q931_IE_E2E_TRANSIT_DELAY        0x42    /* End-to-end Transit Delay */
#define Q931_IE_TD_SELECTION_AND_INT     0x43    /* Transit Delay Selection and Indication */
#define Q931_IE_PL_BINARY_PARAMETERS     0x44    /* Packet layer binary parameters */
#define Q931_IE_PL_WINDOW_SIZE           0x45    /* Packet layer window size */
#define Q931_IE_PACKET_SIZE              0x46    /* Packet size */
#define Q931_IE_CUG                      0x47    /* Closed user group */
#define Q931_IE_REVERSE_CHARGE_IND       0x4A    /* Reverse charging indication */
#define Q931_IE_CONNECTED_NUMBER_DEFAULT 0x4C    /* Connected Number */
#define Q931_IE_INTERFACE_SERVICE        0x66    /* q931+ Interface Service */
#define Q931_IE_CHANNEL_STATUS           0x67    /* q931+ Channel Status */
#define Q931_IE_VERSION_INFO             0x68    /* q931+ Version Info */
#define Q931_IE_CALLING_PARTY_NUMBER     0x6C    /* Calling Party Number */
#define Q931_IE_CALLING_PARTY_SUBADDR    0x6D    /* Calling Party Subaddress */
#define Q931_IE_CALLED_PARTY_NUMBER      0x70    /* Called Party Number */
#define Q931_IE_CALLED_PARTY_SUBADDR     0x71    /* Called Party Subaddress */
#define Q931_IE_REDIRECTING_NUMBER       0x74
#define Q931_IE_REDIRECTION_NUMBER       0x76
#define Q931_IE_TRANSIT_NETWORK_SEL      0x78    /* Transit Network Selection */
#define Q931_IE_RESTART_INDICATOR        0x79
#define Q931_IE_LOW_LAYER_COMPAT         0x7C    /* Low-Layer Compatibility */
#define Q931_IE_HIGH_LAYER_COMPAT        0x7D    /* High-Layer Compatibility */
#define Q931_IE_USER_USER                0x7E    /* User-User */
#define Q931_IE_ESCAPE                   0x7F    /* Escape for extension */

/*
 * Codeset 0 ETSI.
 */
#define Q931_IE_CONNECTED_NUMBER         0x8C
#define Q931_IE_CONNECTED_SUBADDR        0x8D

/*
 * Codeset 5 (National-specific) Belgium.
 */
#define Q931_IE_CHARGING_ADVICE          0x1A

/*
 * Codeset 5 (National-specific) Bellcore National ISDN.
 */
#define Q931_IE_OPERATOR_SYSTEM_ACCESS   0x1D

/*
 * Codeset 5 ETSI ETS 300 192
 */
#define Q931_IE_PARTY_CATEGORY           0x32

/*
 * Codeset 6 (Network-specific) Belgium.
 */
/* 0x1A is Charging Advice, as with Codeset 5 */
#define Q931_IE_REDIRECTING_NUMBER       0x74

/*
 * Codeset 6 (Network-specific) FT-Numeris.
 */
/* 0x1D is User Capability */

/*
 * Codeset 6 (Network-specific) Bellcore National ISDN.
 */
#define Q931_IE_REDIRECTING_SUBADDR      0x75    /* Redirecting Subaddress */
/* 0x76 is Redirection Number, but that's also Codeset 0 */
#define Q931_IE_CALL_APPEARANCE          0x7B

/* Codeset 0 */
static const value_string q931_info_element_vals0[] = {
    { Q931_IE_SEGMENTED_MESSAGE,        "Segmented message" },
    { Q931_IE_CHANGE_STATUS,            "Change status" },
    { Q931_IE_BEARER_CAPABILITY,        "Bearer capability" },
    { Q931_IE_CAUSE,                    "Cause" },
    { Q931_IE_CALL_IDENTITY,            "Call identity" },
    { Q931_IE_CALL_STATE,               "Call state" },
    { Q931_IE_CHANNEL_IDENTIFICATION,   "Channel identification" },
    { Q931_IE_FACILITY,                 "Facility" },
    { Q931_IE_PROGRESS_INDICATOR,       "Progress indicator" },
    { Q931_IE_NETWORK_SPECIFIC_FACIL,   "Network specific facilities" },
    { Q931_IE_NOTIFICATION_INDICATOR,   "Notification indicator" },
    { Q931_IE_DISPLAY,                  "Display" },
    { Q931_IE_DATE_TIME,                "Date/Time" },
    { Q931_IE_KEYPAD_FACILITY,          "Keypad facility" },
    { Q931_IE_INFORMATION_REQUEST,      "Information request" },
    { Q931_IE_SIGNAL,                   "Signal" },
    { Q931_IE_SWITCHHOOK,               "Switchhook" },
    { Q931_IE_FEATURE_ACTIVATION,       "Feature activation" },
    { Q931_IE_FEATURE_INDICATION,       "Feature Indication" },
    { Q931_IE_ENDPOINT_IDENTIFIER,      "Endpoint identifier" },
    { Q931_IE_SERVICE_PROFILE_ID,       "Service profile ID" },
    { Q931_IE_INFORMATION_RATE,         "Information rate" },
    { Q931_IE_E2E_TRANSIT_DELAY,        "End-to-end transit delay" },
    { Q931_IE_TD_SELECTION_AND_INT,     "Transit delay selection and indication" },
    { Q931_IE_PL_BINARY_PARAMETERS,     "Packet layer binary parameters" },
    { Q931_IE_PL_WINDOW_SIZE,           "Packet layer window size" },
    { Q931_IE_PACKET_SIZE,              "Packet size" },
    { Q931_IE_CUG,                      "Closed user group" },
    { Q931_IE_REVERSE_CHARGE_IND,       "Reverse charging indication" },
    { Q931_IE_CONNECTED_NUMBER_DEFAULT, "Connected number" },
    { Q931_IE_INTERFACE_SERVICE,        "Interface Service" },
    { Q931_IE_CHANNEL_STATUS,           "Channel Status" },
    { Q931_IE_VERSION_INFO,             "Version Info" },
    { Q931_IE_CALLING_PARTY_NUMBER,     "Calling party number" },
    { Q931_IE_CALLING_PARTY_SUBADDR,    "Calling party subaddress" },
    { Q931_IE_CALLED_PARTY_NUMBER,      "Called party number" },
    { Q931_IE_CALLED_PARTY_SUBADDR,     "Called party subaddress" },
    { Q931_IE_REDIRECTING_NUMBER,       "Redirecting number" },
    { Q931_IE_REDIRECTION_NUMBER,       "Redirection number" },
    { Q931_IE_TRANSIT_NETWORK_SEL,      "Transit network selection" },
    { Q931_IE_RESTART_INDICATOR,        "Restart indicator" },
    { Q931_IE_LOW_LAYER_COMPAT,         "Low-layer compatibility" },
    { Q931_IE_HIGH_LAYER_COMPAT,        "High-layer compatibility" },
    { Q931_IE_USER_USER,                "User-user" },
    { Q931_IE_ESCAPE,                   "Escape" },
    { Q931_IE_CONNECTED_NUMBER,         "Connected number" },
    { Q931_IE_CONNECTED_SUBADDR,        "Connected subaddress" },
    { 0,                                NULL }
};

/* Codeset 1 */
static const value_string q931_info_element_vals1[] = {
    { 0,                                NULL }
};
/* Codeset 2 */
static const value_string q931_info_element_vals2[] = {
    { 0,                                NULL }
};
/* Codeset 3 */
static const value_string q931_info_element_vals3[] = {
    { 0,                                NULL }
};
/* Codeset 4 */
static const value_string q931_info_element_vals4[] = {
    { 0,                                NULL }
};
/* Codeset 5 */
static const value_string q931_info_element_vals5[] = {
    { Q931_IE_CHARGING_ADVICE,          "Charging advice" },
    { Q931_IE_OPERATOR_SYSTEM_ACCESS,   "Operator system access" },
    { Q931_IE_PARTY_CATEGORY,           "Party category"},
    { 0,                                NULL }
};
/* Codeset 6 */
static const value_string q931_info_element_vals6[] = {
    { Q931_IE_REDIRECTING_NUMBER,       "Redirecting number" },
    { Q931_IE_REDIRECTING_SUBADDR,      "Redirecting subaddress" },
    { Q931_IE_CALL_APPEARANCE,          "Call appearance" },
    { Q931_IE_DISPLAY,                  "Avaya Display" }, /* if Avaya codeset to send display = 6 */
    { 0,                                NULL }
};
/* Codeset 7 */
static const value_string q931_info_element_vals7[] = {
    { 0,                                NULL }
};

/* Codeset array */
#define NUM_INFO_ELEMENT_VALS   (Q931_IE_SHIFT_CODESET+1)
static const value_string *q931_info_element_vals[NUM_INFO_ELEMENT_VALS] = {
    q931_info_element_vals0,
    q931_info_element_vals1,
    q931_info_element_vals2,
    q931_info_element_vals3,
    q931_info_element_vals4,
    q931_info_element_vals5,
    q931_info_element_vals6,
    q931_info_element_vals7,
};

static const value_string q931_congestion_level_vals[] = {
    { 0x0, "Receiver ready" },
    { 0xF, "Receiver not ready" },
    { 0,   NULL }
};

static const value_string q931_repeat_indication_vals[] = {
    { 0x2, "Prioritized list" },
    { 0,   NULL }
};

/*
 * ITU-standardized coding.
 */
#define Q931_ITU_STANDARDIZED_CODING    0x00
#define Q931_ISO_IEC_STANDARDIZED_CODING     0x01

/*
 * Dissect a Segmented message information element.
 */
static void
dissect_q931_segmented_message_ie(tvbuff_t *tvb, packet_info *pinfo, int offset, int len,
    proto_tree *tree, proto_item* item)
{
    guint8 octet;

    if (len != 2) {
        expert_add_info_format(pinfo, item, &ei_q931_invalid_length,
            "Segmented message: length is %d, should be 2", len);
        return;
    }

    octet = tvb_get_guint8(tvb, offset);
    if (octet & 0x80) {
        proto_tree_add_uint_format_value(tree, hf_q931_first_segment, tvb, offset, 1,
            octet & 0x7F, "%u segments remaining", octet & 0x7F);
    } else {
        proto_tree_add_uint_format_value(tree, hf_q931_not_first_segment, tvb, offset, 1,
            octet & 0x7F, "%u segments remaining", octet & 0x7F);
    }
    proto_tree_add_item(tree, hf_q931_segment_type, tvb, offset + 1, 1, ENC_BIG_ENDIAN);
}

/*
 * Dissect a Bearer capability or Low-layer compatibility information element.
 */
static const value_string q931_coding_standard_vals[] = {
    { 0x0, "ITU-T standardized coding" },
    { 0x1, "ISO/IEC standard" },
    { 0x2, "National standard" },
    { 0x3, "Standard defined for this particular network" },
    { 0,    NULL }
};

static const value_string q931_information_transfer_capability_vals[] = {
    { 0x00, "Speech" },
    { 0x08, "Unrestricted digital information" },
    { 0x09, "Restricted digital information" },
    { 0x10, "3.1 kHz audio" },
    { 0x11, "Unrestricted digital information with tones/announcements" },
    { 0x18, "Video" },
    { 0,    NULL }
};

static const value_string q931_transfer_mode_vals[] = {
    { 0x00, "Circuit mode" },
    { 0x02, "Packet mode" },
    { 0,    NULL }
};

#define Q931_IT_RATE_MULTIRATE  0x18

static const value_string q931_information_transfer_rate_vals[] = {
    { 0x00,                   "Packet mode" },
    { 0x10,                   "64 kbit/s" },
    { 0x11,                   "2 x 64 kbit/s" },
    { 0x13,                   "384 kbit/s" },
    { 0x15,                   "1536 kbit/s" },
    { 0x17,                   "1920 kbit/s" },
    { Q931_IT_RATE_MULTIRATE, "Multirate (64 kbit/s base rate)" },
    { 0,                      NULL }
};

/*
 * Values 0x0a and 0x0b added from Q.931 Amendment 1 (12/2002)
 */
static const value_string q931_uil1_vals[] = {
    { 0x01, "V.110/I.460/X.30 rate adaption" },
    { 0x02, "Recommendation G.711 u-law" },
    { 0x03, "Recommendation G.711 A-law" },
    { 0x04, "Recommendation G.721 32 kbit/s ADPCM and Recommendation I.460" },
    { 0x05, "Recommendation H.221 and H.242" },
    { 0x06, "Recommendation H.223 and H.245" },
    { 0x07, "Non-ITU-T-standardized rate adaption" },
    { 0x08, "V.120 rate adaption" },
    { 0x09, "X.31 HDLC flag stuffing" },
    { 0x0a, "Recommendation G.728 LD-CELP" },
    { 0x0b, "Recommendation G.729 CS-ACELP" },
    { 0,    NULL }
};
static value_string_ext q931_uil1_vals_ext = VALUE_STRING_EXT_INIT(q931_uil1_vals);

static const value_string q931_l1_user_rate_vals[] = {
    { 0x00, "Rate indicated by E-bits" },
    { 0x01, "0.6 kbit/s" },
    { 0x02, "1.2 kbit/s" },
    { 0x03, "2.4 kbit/s" },
    { 0x04, "3.6 kbit/s" },
    { 0x05, "4.8 kbit/s" },
    { 0x06, "7.2 kbit/s" },
    { 0x07, "8 kbit/s" },
    { 0x08, "9.6 kbit/s" },
    { 0x09, "14.4 kbit/s" },
    { 0x0A, "16 kbit/s" },
    { 0x0B, "19.2 kbit/s" },
    { 0x0C, "32 kbit/s" },
    { 0x0E, "48 kbit/s" },
    { 0x0F, "56 kbit/s" },
    { 0x10, "64 kbit/s "},
    { 0x15, "0.1345 kbit/s" },
    { 0x16, "0.100 kbit/s" },
    { 0x17, "0.075/1.2 kbit/s" },
    { 0x18, "1.2/0.075 kbit/s" },
    { 0x19, "0.050 kbit/s" },
    { 0x1A, "0.075 kbit/s" },
    { 0x1B, "0.110 kbit/s" },
    { 0x1C, "0.150 kbit/s" },
    { 0x1D, "0.200 kbit/s" },
    { 0x1E, "0.300 kbit/s" },
    { 0x1F, "12 kbit/s" },
    { 0,    NULL }
};
static value_string_ext q931_l1_user_rate_vals_ext = VALUE_STRING_EXT_INIT(q931_l1_user_rate_vals);

static const value_string q931_l1_intermediate_rate_vals[] = {
    { 0x20, "8 kbit/s" },
    { 0x40, "16 kbit/s" },
    { 0x60, "32 kbit/s" },
    { 0,    NULL }
};

static const value_string q931_l1_stop_bits_vals[] = {
    { 0x20, "1" },
    { 0x40, "1.5" },
    { 0x60, "2" },
    { 0,    NULL }
};

static const value_string q931_l1_data_bits_vals[] = {
    { 0x08, "5" },
    { 0x10, "7" },
    { 0x18, "8" },
    { 0,    NULL }
};

static const value_string q931_l1_parity_vals[] = {
    { 0x00, "Odd" },
    { 0x02, "Even" },
    { 0x03, "None" },
    { 0x04, "Forced to 0" },
    { 0x05, "Forced to 1" },
    { 0,    NULL }
};

#define Q931_UIL2_USER_SPEC 0x10

static const value_string q931_uil2_vals[] = {
    { 0x01,                "Basic mode ISO 1745" },
    { 0x02,                "Q.921/I.441" },    /* LAPD */
    { 0x06,                "X.25, link layer" },   /* LAPB */
    { 0x07,                "X.25 multilink" }, /* or 0x0F? */
    { 0x08,                "T.71 Extended LAPB" },
    { 0x09,                "HDLC ARM" },
    { 0x0A,                "HDLC NRM" },
    { 0x0B,                "HDLC ABM" },
    { 0x0C,                "ISO 8802/2 LLC" },
    { 0x0D,                "X.75 Single Link Procedure" },
    { 0x0E,                "Q.922" },
    { 0x0F,                "Core aspects of Q.922" },
    { Q931_UIL2_USER_SPEC, "User-specified" },
    { 0x11,                "ISO 7776 DTE-DTE operation" },
    { 0,                   NULL }
};
static value_string_ext q931_uil2_vals_ext = VALUE_STRING_EXT_INIT(q931_uil2_vals);

static const value_string q931_mode_vals[] = {
    { 0x20, "Normal mode" },
    { 0x40, "Extended mode" },
    { 0,    NULL }
};

#define Q931_UIL3_X25_PL    0x06
#define Q931_UIL3_ISO_8208  0x07    /* X.25-based */
#define Q931_UIL3_X223      0x08    /* X.25-based */
#define Q931_UIL3_TR_9577   0x0B
#define Q931_UIL3_USER_SPEC 0x10

static const value_string q931_uil3_vals[] = {
    { 0x02,                "Q.931/I.451" },
    { Q931_UIL3_X25_PL,    "X.25, packet layer" },
    { Q931_UIL3_ISO_8208,  "ISO/IEC 8208" },
    { Q931_UIL3_X223,      "X.223/ISO 8878" },
    { 0x09,                "ISO/IEC 8473" },
    { 0x0A,                "T.70" },
    { Q931_UIL3_TR_9577,   "ISO/IEC TR 9577" },
    { Q931_UIL3_USER_SPEC, "User-specified" },
    { 0,                   NULL }
};

static void
dissect_q931_protocol_discriminator(tvbuff_t *tvb, int offset, proto_tree *tree)
{
    unsigned int discriminator = tvb_get_guint8(tvb, offset);

    if (discriminator == NLPID_DMS) {
        proto_tree_add_uint_format_value(tree, hf_q931_discriminator,
             tvb, offset, 1, discriminator,
             "Maintenance messages");
    } else if (discriminator == NLPID_Q_931) {
        proto_tree_add_uint_format_value(tree, hf_q931_discriminator,
             tvb, offset, 1, discriminator,
             "Q.931");
    } else if (discriminator == NLPID_Q_2931) {
        proto_tree_add_uint_format_value(tree, hf_q931_discriminator,
             tvb, offset, 1, discriminator,
             "Q.2931");
    } else if ((discriminator >= 16 && discriminator < 63)
        || ((discriminator >= 80) && (discriminator < 254))) {
        proto_tree_add_uint_format_value(tree, hf_q931_discriminator,
            tvb, offset, 1, discriminator,
            "Network layer or layer 3 protocol (0x%02X)",
            discriminator);
    } else if (discriminator >= 64 && discriminator <= 79) {
        proto_tree_add_uint_format_value(tree, hf_q931_discriminator,
            tvb, offset, 1, discriminator,
            "National use (0x%02X)",
            discriminator);
    } else {
        proto_tree_add_uint_format_value(tree, hf_q931_discriminator,
            tvb, offset, 1, discriminator,
            "Reserved (0x%02X)",
            discriminator);
    }
}

static const value_string q931_bearer_capability_layer_ident_vals[] = {
    { 0x01, "Layer 1 identifier" },
    { 0x02, "Layer 2 identifier" },
    { 0x03, "Layer 3 identifier" },
    { 0x00, NULL }
};

#define Q931_UIL2_USER_SPEC 0x10

static const range_string q931_l1_modem_type_rvals[] = {
    { 0x00, 0x05, "National use" },
    { 0x11, 0x11, "V.21" },
    { 0x12, 0x12, "V.22" },
    { 0x13, 0x13, "V.22 bis" },
    { 0x14, 0x14, "V.23" },
    { 0x15, 0x15, "V.26" },
    { 0x16, 0x16, "V.26 bis" },
    { 0x17, 0x17, "V.26 ter" },
    { 0x18, 0x18, "V.27" },
    { 0x19, 0x19, "V.27 bis" },
    { 0x1A, 0x1A, "V.27 ter" },
    { 0x1B, 0x1B, "V.29" },
    { 0x1C, 0x1C, "V.32" },
    { 0x1E, 0x1E, "V.34" },
    { 0x20, 0x2F, "National use" },
    { 0x30, 0x3F, "User specified" },
    { 0, 0,       NULL }
};

static const true_false_string tfs_assignor_default                   = { "Assignor only", "Default assignee" };
static const true_false_string tfs_in_out_band                        = { "in-band", "out-of-band" };
static const true_false_string tfs_protocol_negotiation               = { "Full protocol negotiation", "LLI = 256 only" };

void
dissect_q931_bearer_capability_ie(tvbuff_t *tvb, int offset, int len,
    proto_tree *tree)
{
    guint8 octet;
    guint8 coding_standard;
    guint8 it_rate;
    guint8 uil2_protocol;
    guint8 uil3_protocol;
    guint8 add_l3_info;

    if (len == 0)
        return;
    octet = tvb_get_guint8(tvb, offset);
    coding_standard = octet & 0x60;
    if (coding_standard != Q931_ITU_STANDARDIZED_CODING) {
        /*
         * We don't know how the bearer capability is encoded,
         * so just dump it as data and be done with it.
         */
        proto_tree_add_item(tree, hf_q931_bearer_capability_data, tvb, offset, len, ENC_NA);
        proto_tree_add_boolean(tree, hf_q931_extension_ind, tvb, offset, 1, octet);
        proto_tree_add_uint(tree, hf_q931_coding_standard, tvb, offset, 1, octet);
        return;
    }
    proto_tree_add_boolean(tree, hf_q931_extension_ind, tvb, offset, 1, octet);
    proto_tree_add_uint(tree, hf_q931_coding_standard, tvb, offset, 1, octet);
    proto_tree_add_uint(tree, hf_q931_information_transfer_capability, tvb, offset, 1, octet);
    offset += 1;
    len -= 1;

    /*
     * XXX - only in Low-layer compatibility information element.
     */
    if (!(octet & Q931_IE_VL_EXTENSION)) {
        if (len == 0)
            return;
        proto_tree_add_item(tree, hf_q931_out_band_negotiation, tvb, offset, 1, ENC_NA);
        offset += 1;
        len -= 1;
    }

    if (len == 0)
        return;
    octet = tvb_get_guint8(tvb, offset);
    proto_tree_add_boolean(tree, hf_q931_extension_ind, tvb, offset, 1, octet);
    proto_tree_add_uint(tree, hf_q931_transfer_mode, tvb, offset, 1, octet);
    proto_tree_add_uint(tree, hf_q931_information_transfer_rate, tvb, offset, 1, octet);
    it_rate = octet & 0x1F;
    offset += 1;
    len -= 1;

    if (it_rate == Q931_IT_RATE_MULTIRATE) {
        if (len == 0)
            return;
        proto_tree_add_item(tree, hf_q931_bearer_capability_rate_multiplier, tvb, offset, 1, ENC_BIG_ENDIAN);
        offset += 1;
        len -= 1;
    }

    if (len == 0)
        return;
    octet = tvb_get_guint8(tvb, offset);
    if ((octet & 0x60) == 0x20) {
        /*
         * Layer 1 information.
         */
        proto_tree_add_boolean(tree, hf_q931_extension_ind, tvb, offset, 1, octet);
        proto_tree_add_uint(tree, hf_q931_layer_ident, tvb, offset, 1, octet);
        proto_tree_add_uint(tree, hf_q931_uil1, tvb, offset, 1, octet);
        offset += 1;
        len -= 1;

        if (octet & Q931_IE_VL_EXTENSION)
            goto l1_done;
        if (len == 0)
            return;
        octet = tvb_get_guint8(tvb, offset);
        proto_tree_add_item(tree, hf_q931_layer_1, tvb, offset, 1, ENC_NA);
        proto_tree_add_item(tree, hf_q931_layer_1_in_band_negotiation, tvb, offset, 1, ENC_NA);
        proto_tree_add_item(tree, hf_q931_bearer_capability_user_rate, tvb, offset, 1, ENC_BIG_ENDIAN);
        offset += 1;
        len -= 1;

        if (octet & Q931_IE_VL_EXTENSION)
            goto l1_done;
        if (len == 0)
            return;
        octet = tvb_get_guint8(tvb, offset);
        proto_tree_add_item(tree, hf_q931_bearer_capability_intermediate_rate, tvb, offset, 1, ENC_BIG_ENDIAN);
        proto_tree_add_item(tree, hf_q931_send_data_net_independent_clock, tvb, offset, 1, ENC_NA);
        proto_tree_add_item(tree, hf_q931_accept_data_net_independent_clock, tvb, offset, 1, ENC_NA);
        proto_tree_add_item(tree, hf_q931_send_data_flow_control, tvb, offset, 1, ENC_NA);
        proto_tree_add_item(tree, hf_q931_accept_data_flow_control, tvb, offset, 1, ENC_NA);
        offset += 1;
        len -= 1;

        if (octet & Q931_IE_VL_EXTENSION)
            goto l1_done;
        if (len == 0)
            return;
        octet = tvb_get_guint8(tvb, offset);
        proto_tree_add_item(tree, hf_q931_rate_adaption_header, tvb, offset, 1, ENC_NA);
        proto_tree_add_item(tree, hf_q931_multiple_frame_establishment, tvb, offset, 1, ENC_NA);
        proto_tree_add_item(tree, hf_q931_mode_of_operation, tvb, offset, 1, ENC_NA);
        proto_tree_add_item(tree, hf_q931_protocol_negotiation, tvb, offset, 1, ENC_NA);
        proto_tree_add_item(tree, hf_q931_message_originator, tvb, offset, 1, ENC_NA);
        proto_tree_add_item(tree, hf_q931_negotiation_is_done, tvb, offset, 1, ENC_NA);
        offset += 1;
        len -= 1;

        if (octet & Q931_IE_VL_EXTENSION)
            goto l1_done;
        if (len == 0)
            return;
        octet = tvb_get_guint8(tvb, offset);
        proto_tree_add_item(tree, hf_q931_bearer_capability_stop_bits, tvb, offset, 1, ENC_BIG_ENDIAN);
        proto_tree_add_item(tree, hf_q931_bearer_capability_data_bits, tvb, offset, 1, ENC_BIG_ENDIAN);
        proto_tree_add_item(tree, hf_q931_bearer_capability_parity, tvb, offset, 1, ENC_BIG_ENDIAN);

        if (octet & Q931_IE_VL_EXTENSION)
            goto l1_done;
        proto_tree_add_item(tree, hf_q931_bearer_capability_duplex, tvb, offset, 1, ENC_NA);
        proto_tree_add_item(tree, hf_q931_bearer_capability_modem_type, tvb, offset, 1, ENC_BIG_ENDIAN);
        offset += 1;
        len -= 1;
    }
l1_done:
    ;

    if (len == 0)
        return;
    octet = tvb_get_guint8(tvb, offset);
    if ((octet & 0x60) == 0x40) {
        /*
         * Layer 2 information.
         */
        proto_tree_add_boolean(tree, hf_q931_extension_ind, tvb, offset, 1, octet);
        proto_tree_add_uint(tree, hf_q931_layer_ident, tvb, offset, 1, octet);
        uil2_protocol = octet & 0x1F;
        proto_tree_add_item(tree, hf_q931_uil2, tvb, offset, 1, ENC_BIG_ENDIAN);
        offset += 1;
        len -= 1;

        /*
         * XXX - only in Low-layer compatibility information element.
         */
        if (octet & Q931_IE_VL_EXTENSION)
            goto l2_done;
        if (len == 0)
            return;
        octet = tvb_get_guint8(tvb, offset);
        if (uil2_protocol == Q931_UIL2_USER_SPEC) {
            proto_tree_add_item(tree, hf_q931_uil2_info, tvb, offset, 1, ENC_BIG_ENDIAN);
        } else {
            proto_tree_add_item(tree, hf_q931_bearer_capability_mode, tvb, offset, 1, ENC_BIG_ENDIAN);
        }
        offset += 1;
        len -= 1;

        if (octet & Q931_IE_VL_EXTENSION)
            goto l2_done;
        if (len == 0)
            return;
        octet = tvb_get_guint8(tvb, offset) & 0x7F;
        proto_tree_add_uint_format_value(tree, hf_q931_bearer_capability_window_size, tvb, offset, 1,
            octet, "octet & 0x7F%u k", octet);
        offset += 1;
        len -= 1;
    }
l2_done:
    ;

    if (len == 0)
        return;
    octet = tvb_get_guint8(tvb, offset);
    if ((octet & 0x60) == 0x60) {
        /*
         * Layer 3 information.
         */
        proto_tree_add_boolean(tree, hf_q931_extension_ind, tvb, offset, 1, octet);
        proto_tree_add_uint(tree, hf_q931_layer_ident, tvb, offset, 1, octet);
        uil3_protocol = octet & 0x1F;
        proto_tree_add_item(tree, hf_q931_uil3, tvb, offset, 1, ENC_BIG_ENDIAN);
        offset += 1;
        len -= 1;


        /*
         * XXX - only in Low-layer compatibility information element.
         */
        if (octet & Q931_IE_VL_EXTENSION)
            goto l3_done;
        if (len == 0)
            return;
        octet = tvb_get_guint8(tvb, offset);
        switch (uil3_protocol) {

        case Q931_UIL3_X25_PL:
        case Q931_UIL3_ISO_8208:
        case Q931_UIL3_X223:
            proto_tree_add_item(tree, hf_q931_bearer_capability_mode, tvb, offset, 1, ENC_BIG_ENDIAN);
            offset += 1;
            len -= 1;

            if (octet & Q931_IE_VL_EXTENSION)
                goto l3_done;
            if (len == 0)
                return;
            octet = tvb_get_guint8(tvb, offset);
            proto_tree_add_item(tree, hf_q931_bearer_capability_default_packet_size, tvb, offset, 1, ENC_BIG_ENDIAN);
            offset += 1;
            len -= 1;

            if (octet & Q931_IE_VL_EXTENSION)
                goto l3_done;
            if (len == 0)
                return;
            proto_tree_add_item(tree, hf_q931_bearer_capability_packet_window_size, tvb, offset, 1, ENC_BIG_ENDIAN);
            /*offset += 1;*/
            /*len -= 1;*/
            break;

        case Q931_UIL3_USER_SPEC:
            proto_tree_add_uint_format_value(tree, hf_q931_bearer_capability_default_packet_size, tvb, offset, 1,
                1 << (octet & 0x0F), "%u octets", 1 << (octet & 0x0F));
            /*offset += 1;*/
            /*len -= 1;*/
            break;

        case Q931_UIL3_TR_9577:
            add_l3_info = (octet & 0x0F) << 4;
            if (octet & Q931_IE_VL_EXTENSION)
                goto l3_done;
            if (len < 2)
                return;
            octet = tvb_get_guint8(tvb, offset + 1);
            add_l3_info |= (octet & 0x0F);
            proto_tree_add_uint(tree, hf_q931_uil3_additional, tvb, offset, 2, add_l3_info);
            /*offset += 2;*/
            /*len -= 2;*/
            break;
        }
    }
l3_done:
    ;
}

/*
 * Dissect a Cause information element.
 */


static const value_string q931_cause_location_vals[] = {
    { 0x00, "User (U)" },
    { 0x01, "Private network serving the local user (LPN)" },
    { 0x02, "Public network serving the local user (LN)" },
    { 0x03, "Transit network (TN)" },
    { 0x04, "Public network serving the remote user (RLN)" },
    { 0x05, "Private network serving the remote user (RPN)" },
    { 0x06, "Unallocated code" },
    { 0x07, "International network (INTL)" },
    { 0x08, "Unallocated code" },
    { 0x09, "Unallocated code" },
    { 0x0A, "Network beyond interworking point (BI)" },
    { 0,    NULL }
};
value_string_ext q931_cause_location_vals_ext = VALUE_STRING_EXT_INIT(q931_cause_location_vals);

static const value_string q931_cause_recommendation_vals[] = {
    { 0x00, "Q.931" },
    { 0x03, "X.21" },
    { 0x04, "X.25" },
    { 0x05, "Q.1031/Q.1051" },
    { 0,    NULL }
};

/*
 * Cause codes for Cause.
 */
#define Q931_CAUSE_UNALLOC_NUMBER   0x01
#define Q931_CAUSE_NO_ROUTE_TO_DEST 0x03
#define Q931_CAUSE_CALL_REJECTED    0x15
#define Q931_CAUSE_NUMBER_CHANGED   0x16
#define Q931_CAUSE_ACCESS_INFO_DISC 0x2B
#define Q931_CAUSE_QOS_UNAVAILABLE  0x31
#define Q931_CAUSE_CHAN_NONEXISTENT 0x52
#define Q931_CAUSE_INCOMPATIBLE_DEST    0x58
#define Q931_CAUSE_MAND_IE_MISSING  0x60
#define Q931_CAUSE_MT_NONEX_OR_UNIMPL   0x61
#define Q931_CAUSE_IE_NONEX_OR_UNIMPL   0x63
#define Q931_CAUSE_INVALID_IE_CONTENTS  0x64
#define Q931_CAUSE_MSG_INCOMPAT_W_CS    0x65
#define Q931_CAUSE_REC_TIMER_EXP    0x66

static const value_string q931_cause_code_vals[] = {
    { 0x00,                                "Valid cause code not yet received" },
    { Q931_CAUSE_UNALLOC_NUMBER,           "Unallocated (unassigned) number" },
    { 0x02,                                "No route to specified transit network" },
    { Q931_CAUSE_NO_ROUTE_TO_DEST,         "No route to destination" },
    { 0x04,                                "Send special information tone" },
    { 0x05,                                "Misdialled trunk prefix" },
    { 0x06,                                "Channel unacceptable" },
    { 0x07,                                "Call awarded and being delivered in an established channel" },
    { 0x08,                                "Prefix 0 dialed but not allowed" },
                    /* Q.850 -             "Preemption" */
    { 0x09,                                "Prefix 1 dialed but not allowed" },
                    /* Q.850 -             "Preemption - circuit reserved for reuse" */
    { 0x0A,                                "Prefix 1 dialed but not required" },
    { 0x0B,                                "More digits received than allowed, call is proceeding" },
    { 0x0E,                                "QoR: ported number" },
    { 0x10,                                "Normal call clearing" },
    { 0x11,                                "User busy" },
    { 0x12,                                "No user responding" },
    { 0x13,                                "No answer from user (user alerted)" },
    { 0x14,                                "Subscriber absent" },
    { Q931_CAUSE_CALL_REJECTED,            "Call rejected" },
    { Q931_CAUSE_NUMBER_CHANGED,           "Number changed" },
    { 0x17,                                "Reverse charging rejected" },
                    /* Q.850 -             "Redirection to new destination" */
    { 0x18,                                "Call suspended" },
                    /* Q.850 Amendment 1 - "Call rejected due to feature at the destination" */
    { 0x19,                                "Call resumed" },
                    /* Q.850 -             "Exchange routing error */
    { 0x1A,                                "Non-selected user clearing" },
    { 0x1B,                                "Destination out of order" },
    { 0x1C,                                "Invalid number format (incomplete number)" },
    { 0x1D,                                "Facility rejected" },
    { 0x1E,                                "Response to STATUS ENQUIRY" },
    { 0x1F,                                "Normal unspecified" },
    { 0x21,                                "Circuit out of order" },
    { 0x22,                                "No circuit/channel available" },
    { 0x23,                                "Destination unattainable" },
    { 0x25,                                "Degraded service" },
    { 0x26,                                "Network out of order" },
    { 0x27,                                "Transit delay range cannot be achieved" },
                    /* Q.850 -             "Permanent frame mode connection out of service" */
    { 0x28,                                "Throughput range cannot be achieved" },
                    /* Q.850 -             "Permanent frame mode connection operational" */
    { 0x29,                                "Temporary failure" },
    { 0x2A,                                "Switching equipment congestion" },
    { Q931_CAUSE_ACCESS_INFO_DISC,         "Access information discarded" },
    { 0x2C,                                "Requested circuit/channel not available" },
    { 0x2D,                                "Pre-empted" },
    { 0x2E,                                "Precedence call blocked" },
    { 0x2F,                                "Resources unavailable, unspecified" },
    { Q931_CAUSE_QOS_UNAVAILABLE,          "Quality of service unavailable" },
    { 0x32,                                "Requested facility not subscribed" },
    { 0x33,                                "Reverse charging not allowed" },
    { 0x34,                                "Outgoing calls barred" },
    { 0x35,                                "Outgoing calls barred within CUG" },
    { 0x36,                                "Incoming calls barred" },
    { 0x37,                                "Incoming calls barred within CUG" },
    { 0x38,                                "Call waiting not subscribed" },
    { 0x39,                                "Bearer capability not authorized" },
    { 0x3A,                                "Bearer capability not presently available" },
    { 0x3E,                                "Inconsistency in designated outgoing access information and subscriber class" },
    { 0x3F,                                "Service or option not available, unspecified" },
    { 0x41,                                "Bearer capability not implemented" },
    { 0x42,                                "Channel type not implemented" },
    { 0x43,                                "Transit network selection not implemented" },
    { 0x44,                                "Message not implemented" },
    { 0x45,                                "Requested facility not implemented" },
    { 0x46,                                "Only restricted digital information bearer capability is available" },
    { 0x4F,                                "Service or option not implemented, unspecified" },
    { 0x51,                                "Invalid call reference value" },
    { Q931_CAUSE_CHAN_NONEXISTENT,         "Identified channel does not exist" },
    { 0x53,                                "Call identity does not exist for suspended call" },
    { 0x54,                                "Call identity in use" },
    { 0x55,                                "No call suspended" },
    { 0x56,                                "Call having the requested call identity has been cleared" },
    { 0x57,                                "Called user not member of CUG" },
    { Q931_CAUSE_INCOMPATIBLE_DEST,        "Incompatible destination" },
    { 0x59,                                "Non-existent abbreviated address entry" },
    { 0x5A,                                "Destination address missing, and direct call not subscribed" },
                                           /* Q.850 -             "Non-existent CUG" */
    { 0x5B,                                "Invalid transit network selection (national use)" },
    { 0x5C,                                "Invalid facility parameter" },
    { 0x5D,                                "Mandatory information element is missing" },
    { 0x5F,                                "Invalid message, unspecified" },
    { Q931_CAUSE_MAND_IE_MISSING,          "Mandatory information element is missing" },
    { Q931_CAUSE_MT_NONEX_OR_UNIMPL,       "Message type non-existent or not implemented" },
    { 0x62,                                "Message not compatible with call state or message type non-existent or not implemented" },
    { Q931_CAUSE_IE_NONEX_OR_UNIMPL,       "Information element non-existent or not implemented" },
    { Q931_CAUSE_INVALID_IE_CONTENTS,      "Invalid information element contents" },
    { Q931_CAUSE_MSG_INCOMPAT_W_CS,        "Message not compatible with call state" },
    { Q931_CAUSE_REC_TIMER_EXP,            "Recovery on timer expiry" },
    { 0x67,                                "Parameter non-existent or not implemented - passed on" },
    { 0x6E,                                "Message with unrecognized parameter discarded" },
    { 0x6F,                                "Protocol error, unspecified" },
    { 0x7F,                                "Internetworking, unspecified" },
    { 0,                                   NULL }
};
value_string_ext q931_cause_code_vals_ext = VALUE_STRING_EXT_INIT(q931_cause_code_vals);

static const value_string q931_cause_condition_vals[] = {
    { 0x00, "Unknown" },
    { 0x01, "Permanent" },
    { 0x02, "Transient" },
    { 0x00, NULL }
};

#define Q931_REJ_USER_SPECIFIC   0x00
#define Q931_REJ_IE_MISSING      0x04
#define Q931_REJ_IE_INSUFFICIENT 0x08

static const value_string q931_rejection_reason_vals[] = {
    { 0x00, "User specific" },
    { 0x04, "Information element missing" },
    { 0x08, "Information element contents are not sufficient" },
    { 0x00, NULL }
};

static const gchar *get_message_name(guint8 prot_discr, guint8 message_type) {
    if (prot_discr == NLPID_DMS)
        return val_to_str(message_type, dms_message_type_vals, "Unknown (0x%02X)");
    else
        return val_to_str_ext(message_type, &q931_message_type_vals_ext, "Unknown (0x%02X)");
}

static const true_false_string tfs_user_provider = { "User", "Provider" };
static const true_false_string tfs_abnormal_normal = { "Abnormal", "Normal" };

static void
dissect_q931_cause_ie_unsafe(tvbuff_t *tvb, int offset, int len,
    proto_tree *tree, int hf_cause_value, guint8 *cause_value, const value_string *ie_vals)
{
    guint8 octet;
    guint8 coding_standard;
    guint8 rejection_reason;

    if (len == 0)
        return;
    octet = tvb_get_guint8(tvb, offset);
    coding_standard = octet & 0x60;
    if (coding_standard != Q931_ITU_STANDARDIZED_CODING &&
        !g931_iso_iec_cause && coding_standard != Q931_ISO_IEC_STANDARDIZED_CODING) {
        /*
         * We don't know how the cause is encoded,
         * so just dump it as data and be done with it.
         */
        proto_tree_add_uint(tree, hf_q931_coding_standard, tvb, offset, 1, octet);
        proto_tree_add_item(tree, hf_q931_cause_data, tvb, offset, len, ENC_NA);
        return;
    }
    proto_tree_add_uint(tree, hf_q931_cause_location, tvb, offset, 1, octet);
    proto_tree_add_uint(tree, hf_q931_coding_standard, tvb, offset, 1, octet);
    proto_tree_add_boolean(tree, hf_q931_extension_ind, tvb, offset, 1, octet);
    offset += 1;
    len -= 1;

    if (!(octet & Q931_IE_VL_EXTENSION)) {
        if (len == 0)
            return;
        octet = tvb_get_guint8(tvb, offset);
        proto_tree_add_item(tree, hf_q931_cause_recommendation, tvb, offset, 1, ENC_BIG_ENDIAN);
        proto_tree_add_boolean(tree, hf_q931_extension_ind, tvb, offset, 1, octet);
        offset += 1;
        len -= 1;
    }

    if (len == 0)
        return;
    octet = tvb_get_guint8(tvb, offset);
    *cause_value = octet & 0x7F;

    /* add cause value to packet info for use in tap */
    if(have_valid_q931_pi) {
        q931_pi->cause_value = *cause_value;
    }

    proto_tree_add_uint(tree, hf_cause_value, tvb, offset, 1, *cause_value);
    proto_tree_add_boolean(tree, hf_q931_extension_ind, tvb, offset, 1, octet);
    offset += 1;
    len -= 1;

    if (len == 0)
        return;
    switch (*cause_value) {
    case Q931_CAUSE_UNALLOC_NUMBER:
    case Q931_CAUSE_NO_ROUTE_TO_DEST:
    case Q931_CAUSE_QOS_UNAVAILABLE:
        proto_tree_add_item(tree, hf_q931_network_service, tvb, offset, 1, ENC_NA);
        proto_tree_add_item(tree, hf_q931_extension_condition_type, tvb, offset, 1, ENC_NA);
        proto_tree_add_item(tree, hf_q931_extension_condition, tvb, offset, 1, ENC_BIG_ENDIAN);
        break;

    case Q931_CAUSE_CALL_REJECTED:
        rejection_reason = octet & 0x7C;
        proto_tree_add_item(tree, hf_q931_cause_call_rejection_reason, tvb, offset, 1, ENC_BIG_ENDIAN);
        proto_tree_add_item(tree, hf_q931_cause_call_condition, tvb, offset, 1, ENC_BIG_ENDIAN);
        offset += 1;
        len -= 1;

        if (len == 0)
            return;
        switch (rejection_reason) {

        case Q931_REJ_USER_SPECIFIC:
            proto_tree_add_item(tree, hf_q931_cause_call_user_specific_diagnostic, tvb, offset, len, ENC_NA);
            break;

        case Q931_REJ_IE_MISSING:
            proto_tree_add_uint_format_value(tree, hf_q931_missing_info_element, tvb, offset, 1,
                 tvb_get_guint8(tvb, offset), "%s", val_to_str(tvb_get_guint8(tvb, offset), ie_vals,
                  "Unknown (0x%02X)"));
            break;

        case Q931_REJ_IE_INSUFFICIENT:
            proto_tree_add_uint_format_value(tree, hf_q931_insufficient_info_element, tvb, offset, 1,
                tvb_get_guint8(tvb, offset), "%s", val_to_str(tvb_get_guint8(tvb, offset), ie_vals,
                  "Unknown (0x%02X)"));
            break;

        default:
            proto_tree_add_item(tree, hf_q931_cause_call_diagnostic, tvb, offset, len, ENC_NA);
            break;
        }
        break;

    case Q931_CAUSE_ACCESS_INFO_DISC:
    case Q931_CAUSE_INCOMPATIBLE_DEST:
    case Q931_CAUSE_MAND_IE_MISSING:
    case Q931_CAUSE_IE_NONEX_OR_UNIMPL:
    case Q931_CAUSE_INVALID_IE_CONTENTS:
        do {
            proto_tree_add_uint_format_value(tree, hf_q931_information_element, tvb, offset, 1,
                tvb_get_guint8(tvb, offset), "%s", val_to_str(tvb_get_guint8(tvb, offset), ie_vals,
                  "Unknown (0x%02X)"));
            offset += 1;
            len -= 1;
        } while (len != 0);
        break;

    case Q931_CAUSE_MT_NONEX_OR_UNIMPL:
    case Q931_CAUSE_MSG_INCOMPAT_W_CS:
        proto_tree_add_item(tree, hf_q931_cause_call_message_type, tvb, offset, 1, ENC_BIG_ENDIAN);
        break;

    case Q931_CAUSE_REC_TIMER_EXP:
        if (len < 3)
            return;
        proto_tree_add_item(tree, hf_q931_cause_call_rec_timer, tvb, offset, 3, ENC_NA|ENC_ASCII);
        break;

    default:
        proto_tree_add_item(tree, hf_q931_cause_call_diagnostic, tvb, offset, len, ENC_NA);
    }
}

void
dissect_q931_cause_ie(tvbuff_t *tvb, int offset, int len,
              proto_tree *tree, int hf_cause_value, guint8 *cause_value, const value_string *ie_vals)
{
    gboolean have_valid_q931_pi_save = have_valid_q931_pi;
    have_valid_q931_pi = FALSE;
    dissect_q931_cause_ie_unsafe(tvb, offset, len, tree, hf_cause_value, cause_value, ie_vals);
    have_valid_q931_pi =  have_valid_q931_pi_save;
}

/*
 * Dissect a Change status information element.
 */

static const value_string q931_status_preference_vals[] = {
    { 0x01, "Channel" },
    { 0,    NULL }
};

static const value_string q931_new_status_vals[] = {
    { 0x00, "In Service" },
    { 0x01, "Maintenance" },
    { 0x02, "Out of Service" },
    { 0,    NULL }
};

static void
dissect_q931_change_status_ie(tvbuff_t *tvb, int offset, int len _U_, proto_tree *tree)
{
    if (len == 0)
        return;

    proto_tree_add_item(tree, hf_q931_extension_ind, tvb, offset, 1, ENC_BIG_ENDIAN);
    proto_tree_add_item(tree, hf_q931_extension_ind_preference, tvb, offset, 1, ENC_BIG_ENDIAN);
    proto_tree_add_item(tree, hf_q931_extension_ind_new_status, tvb, offset, 1, ENC_BIG_ENDIAN);
}

/*
 * Dissect a Call state information element.
 */
static const value_string q931_call_state_vals[] = {
    { 0x00, "Null" },
    { 0x01, "Call initiated" },
    { 0x02, "Overlap sending" },
    { 0x03, "Outgoing call proceeding" },
    { 0x04, "Call delivered" },
    { 0x06, "Call present" },
    { 0x07, "Call received" },
    { 0x08, "Connect request" },
    { 0x09, "Incoming call proceeding" },
    { 0x0A, "Active" },
    { 0x0B, "Disconnect request" },
    { 0x0C, "Disconnect indication" },
    { 0x0F, "Suspend request" },
    { 0x11, "Resume request" },
    { 0x13, "Release request" },
    { 0x16, "Call abort"},
    { 0x19, "Overlap receiving" },
    { 0x3D, "Restart request" },
    { 0x3E, "Restart" },
    { 0,    NULL }
};
value_string_ext q931_call_state_vals_ext = VALUE_STRING_EXT_INIT(q931_call_state_vals);

static void
dissect_q931_call_state_ie(tvbuff_t *tvb, int offset, int len,
    proto_tree *tree)
{
    guint8 octet;
    guint8 coding_standard;

    if (len == 0)
        return;
    octet = tvb_get_guint8(tvb, offset);
    coding_standard = octet & 0x60;
    proto_tree_add_uint(tree, hf_q931_coding_standard, tvb, offset, 1, octet);
    if (coding_standard != Q931_ITU_STANDARDIZED_CODING) {
        /*
         * We don't know how the call state is encoded,
         * so just dump it as data and be done with it.
         */
        proto_tree_add_item(tree, hf_q931_call_state_data, tvb, offset, len, ENC_NA);
        return;
    }
    proto_tree_add_item(tree, hf_q931_call_state, tvb, offset, 1, ENC_BIG_ENDIAN);
}

/*
 * Dissect a Channel identification information element.
 */
#define Q931_INTERFACE_IDENTIFIED   0x40
#define Q931_NOT_BASIC_CHANNEL      0x20

static const value_string q931_basic_channel_selection_vals[] = {
    { 0x00, "No channel" },
    { 0x01, "B1 channel" },
    { 0x02, "B2 channel" },
    { 0x03, "Any channel" },
    { 0,    NULL }
};

static const value_string q931_not_basic_channel_selection_vals[] = {
    { 0x00, "No channel" },
    { 0x01, "Channel indicated in following octets" },
    { 0x03, "Any channel" },
    { 0,    NULL }
};

#define Q931_IS_SLOT_MAP        0x10

static const value_string q931_element_type_vals[] = {
    { 0x03, "B-channel units" },
    { 0x06, "H0-channel units" },
    { 0x08, "H11-channel units" },
    { 0x09, "H12-channel units" },
    { 0,    NULL }
};

static void
dissect_q931_channel_identification_ie(tvbuff_t *tvb, int offset, int len,
    proto_tree *tree)
{
    guint8 octet;
    guint8 coding_standard;

    if (len == 0)
        return;
    octet = tvb_get_guint8(tvb, offset);

    proto_tree_add_item(tree, hf_q931_extension_ind, tvb, offset, 1, ENC_BIG_ENDIAN);
    proto_tree_add_item(tree, hf_q931_channel_interface_explicit, tvb, offset, 1, ENC_BIG_ENDIAN);
    proto_tree_add_item(tree, hf_q931_channel_interface_type, tvb, offset, 1, ENC_BIG_ENDIAN);
    proto_tree_add_item(tree, hf_q931_channel_exclusive, tvb, offset, 1, ENC_BIG_ENDIAN);
    proto_tree_add_item(tree, hf_q931_channel_dchan, tvb, offset, 1, ENC_BIG_ENDIAN);

    if (octet & Q931_NOT_BASIC_CHANNEL) {
        proto_tree_add_item(tree, hf_q931_channel_selection_pri, tvb, offset, 1, ENC_BIG_ENDIAN);
    } else {
        proto_tree_add_item(tree, hf_q931_channel_selection_bri, tvb, offset, 1, ENC_BIG_ENDIAN);
    }
    offset += 1;
    len -= 1;

    if (octet & Q931_INTERFACE_IDENTIFIED) {
        guint8 octet2;
        guint32 identifier_val = 0;
        int identifier_offset = offset;
        int identifier_len = 0;
        do {
            if (len == 0)
                break;
            octet2 = tvb_get_guint8(tvb, offset);
            offset += 1;
            len -= 1;
            identifier_len++;
            identifier_val <<= 7;
            identifier_val |= octet2 & 0x7F;
        } while (!(octet2 & Q931_IE_VL_EXTENSION));

        if (identifier_len != 0) {
            proto_tree_add_uint(tree, hf_q931_channel_interface_id, tvb, identifier_offset,
                identifier_len, identifier_val);
        }
    }

    if (octet & Q931_NOT_BASIC_CHANNEL) {
        if (len == 0)
            return;
        octet = tvb_get_guint8(tvb, offset);
        coding_standard = octet & 0x60;
        proto_tree_add_item(tree, hf_q931_extension_ind, tvb, offset, 1, ENC_BIG_ENDIAN);
        proto_tree_add_uint(tree, hf_q931_coding_standard, tvb, offset, 1, octet);
        if (coding_standard != Q931_ITU_STANDARDIZED_CODING) {
            /*
             * We don't know how the channel identifier is
             * encoded, so just dump it as data and be done
             * with it.
             */
            proto_tree_add_item(tree, hf_q931_channel_data, tvb, offset, len, ENC_NA);
            return;
        }
        proto_tree_add_item(tree, hf_q931_channel_map, tvb, offset, 1, ENC_BIG_ENDIAN);
        proto_tree_add_item(tree, hf_q931_channel_element_type, tvb, offset, 1, ENC_BIG_ENDIAN);

        offset += 1;
        len -= 1;

        if (octet & Q931_IS_SLOT_MAP) {
            while (len) {
                proto_tree_add_item(tree, hf_q931_channel_slot_map, tvb, offset, 1, ENC_BIG_ENDIAN);
                offset += 1;
                len -= 1;
            }
        } else {
            guint8 octet2;
            do {
                if (len == 0)
                    break;
                octet2 = tvb_get_guint8(tvb, offset);

                proto_tree_add_item(tree, hf_q931_extension_ind, tvb, offset, 1, ENC_BIG_ENDIAN);
                proto_tree_add_item(tree,hf_q931_channel_number,tvb,offset,1,ENC_BIG_ENDIAN);

                offset += 1;
                len -= 1;
            } while (!(octet2 & Q931_IE_VL_EXTENSION));
        }
    }
}

/*
 * Dissect a Progress indicator information element.
 */
static const value_string q931_progress_description_vals[] = {
    { 0x01, "Call is not end-to-end ISDN - progress information available in-band" },
    { 0x02, "Destination address is non-ISDN" },
    { 0x03, "Origination address is non-ISDN" },
    { 0x04, "Call has returned to the ISDN" },
    { 0x05, "Interworking has occurred and has resulted in a telecommunications service change" },
    { 0x08, "In-band information or an appropriate pattern is now available" },
    { 0,    NULL }
};
value_string_ext q931_progress_description_vals_ext = VALUE_STRING_EXT_INIT(q931_progress_description_vals);

void
dissect_q931_progress_indicator_ie(tvbuff_t *tvb, int offset, int len,
    proto_tree *tree)
{
    guint8 octet;
    guint8 coding_standard;

    if (len == 0)
        return;
    octet = tvb_get_guint8(tvb, offset);
    coding_standard = octet & 0x60;
    proto_tree_add_uint(tree, hf_q931_coding_standard, tvb, offset, 1, octet);
    if (coding_standard != Q931_ITU_STANDARDIZED_CODING) {
        /*
         * We don't know how the progress indicator is encoded,
         * so just dump it as data and be done with it.
         */
        proto_tree_add_item(tree, hf_q931_progress_indicator_data, tvb, offset, len, ENC_NA);
        return;
    }
    proto_tree_add_item(tree, hf_q931_progress_indicator_location, tvb, offset, 1, ENC_BIG_ENDIAN);
    offset += 1;
    len -= 1;

    if (len == 0)
        return;

    proto_tree_add_item(tree, hf_q931_progress_indicator_description, tvb, offset, 1, ENC_BIG_ENDIAN);
}

/*
 * Dissect a Network-specific facilities or Transit network selection
 * information element.
 */
static const value_string q931_netid_type_vals[] = {
    { 0x00, "User specified" },
    { 0x20, "National network identification" },
    { 0x30, "International network identification" },
    { 0,    NULL }
};

static const value_string q931_netid_plan_vals[] = {
    { 0x00, "Unknown" },
    { 0x01, "Carrier Identification Code" },
    { 0x03, "X.121 data network identification code" },
    { 0,    NULL }
};

static void
dissect_q931_ns_facilities_ie(tvbuff_t *tvb, int offset, int len,
    proto_tree *tree)
{
    guint8 octet;
    int netid_len;

    if (len == 0)
        return;
    octet = tvb_get_guint8(tvb, offset);
    netid_len = octet & 0x7F;
    proto_tree_add_item(tree, hf_q931_netid_length, tvb, offset, 1, ENC_BIG_ENDIAN);
    offset += 1;
    len -= 1;
    if (netid_len != 0) {
        if (len == 0)
            return;
        proto_tree_add_item(tree, hf_q931_netid_type, tvb, offset, 1, ENC_BIG_ENDIAN);
        proto_tree_add_item(tree, hf_q931_netid_plan, tvb, offset, 1, ENC_BIG_ENDIAN);
        offset += 1;
        len -= 1;
        netid_len--;

        if (len == 0)
            return;
        if (netid_len > len)
            netid_len = len;
        if (netid_len != 0) {
            proto_tree_add_item(tree, hf_q931_netid, tvb, offset, netid_len, ENC_NA|ENC_ASCII);
            offset += netid_len;
            len -= netid_len;
        }
    }

    /*
     * Whatever is left is the network-specific facility
     * specification.
     */
    if (len == 0)
        return;
    proto_tree_add_item(tree, hf_q931_netid_facility_specification, tvb, offset, len, ENC_NA);
}

/*
 * Dissect a Notification indicator information element.
 */
static const value_string q931_notification_description_vals[] = {
    { 0x00, "User suspended" },
    { 0x01, "User resumed" },
    { 0x02, "Bearer service change" },
    { 0,    NULL }
};

static void
dissect_q931_notification_indicator_ie(tvbuff_t *tvb, int offset, int len,
    proto_tree *tree)
{
    if (len == 0)
        return;

    proto_tree_add_item(tree, hf_q931_notification_description, tvb, offset, 1, ENC_BIG_ENDIAN);
}

/*
 * Dissect a Date/time information element.
 */
static void
dissect_q931_date_time_ie(tvbuff_t *tvb, packet_info* pinfo, int offset, int len,
    proto_tree *tree)
{
    if (len == 6) {
        /*
         * XXX - what is "year" relative to?  Is "month" 0-origin or
         * 1-origin?  Q.931 doesn't say....
         */
        proto_tree_add_bytes_format_value(tree, hf_q931_date_time, tvb, offset, 6, NULL, "%02u-%02u-%02u %02u:%02u:%02u",
            tvb_get_guint8(tvb, offset + 0), tvb_get_guint8(tvb, offset + 1), tvb_get_guint8(tvb, offset + 2),
            tvb_get_guint8(tvb, offset + 3), tvb_get_guint8(tvb, offset + 4), tvb_get_guint8(tvb, offset + 5));
    } else if (len == 5) {
        proto_tree_add_bytes_format_value(tree, hf_q931_date_time, tvb, offset, 5, NULL, "%02u-%02u-%02u %02u:%02u:00",
            tvb_get_guint8(tvb, offset + 0), tvb_get_guint8(tvb, offset + 1), tvb_get_guint8(tvb, offset + 2),
            tvb_get_guint8(tvb, offset + 3), tvb_get_guint8(tvb, offset + 4));
    } else {
        proto_tree_add_expert_format(tree, pinfo, &ei_q931_date_time, tvb, offset, len, "Date/time: length is %d, should be 5 or 6", len);
    }
}

/*
 * Dissect a Signal information element.
 */
static const value_string q931_signal_vals[] = {
    { 0x00, "Dial tone on" },
    { 0x01, "Ring tone on" },
    { 0x02, "Intercept tone on" },
    { 0x03, "Network congestion tone on" }, /* "fast busy" */
    { 0x04, "Busy tone on" },
    { 0x05, "Confirm tone on" },
    { 0x06, "Answer tone on" },
    { 0x07, "Call waiting tone on" },
    { 0x08, "Off-hook warning tone on" },
    { 0x09, "Preemption tone on" },
    { 0x3F, "Tones off" },
    { 0x40, "Alerting on - pattern 0" },
    { 0x41, "Alerting on - pattern 1" },
    { 0x42, "Alerting on - pattern 2" },
    { 0x43, "Alerting on - pattern 3" },
    { 0x44, "Alerting on - pattern 4" },
    { 0x45, "Alerting on - pattern 5" },
    { 0x46, "Alerting on - pattern 6" },
    { 0x47, "Alerting on - pattern 7" },
    { 0x4F, "Alerting off" },
    { 0,    NULL }
};
static value_string_ext q931_signal_vals_ext = VALUE_STRING_EXT_INIT(q931_signal_vals);

static void
dissect_q931_signal_ie(tvbuff_t *tvb, packet_info *pinfo, int offset, int len,
    proto_tree *tree, proto_item* item)
{
    if (len != 1) {
        expert_add_info_format(pinfo, item, &ei_q931_invalid_length,
            "Signal: length is %d, should be 1", len);
        return;
    }
    proto_tree_add_item(tree, hf_q931_signal, tvb, offset, 1, ENC_BIG_ENDIAN);
}

/*
 * Dissect an Information rate information element.
 */
static const value_string q931_throughput_class_vals[] = {
    { 0x03, "75 bit/s" },
    { 0x04, "150 bit/s" },
    { 0x05, "300 bit/s" },
    { 0x06, "600 bit/s" },
    { 0x07, "1200 bit/s" },
    { 0x08, "2400 bit/s" },
    { 0x09, "4800 bit/s" },
    { 0x0A, "9600 bit/s" },
    { 0x0B, "19200 bit/s" },
    { 0x0C, "48000 bit/s" },
    { 0x0D, "64000 bit/s" },
    { 0,    NULL }
};
static value_string_ext q931_throughput_class_vals_ext = VALUE_STRING_EXT_INIT(q931_throughput_class_vals);

static void
dissect_q931_information_rate_ie(tvbuff_t *tvb, packet_info *pinfo, int offset, int len,
    proto_tree *tree, proto_item* item)
{
    if (len != 4) {
        expert_add_info_format(pinfo, item, &ei_q931_invalid_length,
            "Information rate: length is %d, should be 4", len);
        return;
    }
    proto_tree_add_item(tree, hf_q931_information_rate_incoming, tvb, offset + 0, 1, ENC_BIG_ENDIAN);
    proto_tree_add_item(tree, hf_q931_information_rate_outgoing, tvb, offset + 1, 1, ENC_BIG_ENDIAN);
    proto_tree_add_item(tree, hf_q931_information_rate_minimum_incoming, tvb, offset + 2, 1, ENC_BIG_ENDIAN);
    proto_tree_add_item(tree, hf_q931_information_rate_minimum_outgoing, tvb, offset + 3, 1, ENC_BIG_ENDIAN);
}

static int
dissect_q931_guint16_value(tvbuff_t *tvb, packet_info *pinfo, int offset, int len,
    proto_tree *tree, proto_item* item, int hf_value)
{
    guint8 octet;
    guint16 value;
    int value_len;

    value_len = 0;

    octet = tvb_get_guint8(tvb, offset);
    if (octet & Q931_IE_VL_EXTENSION) {
        /*
         * Only one octet long - error.
         */
        goto bad_length;
    }
    value = (octet & 0x3) << 14;
    offset += 1;
    len -= 1;
    value_len++;

    if (len == 0) {
        /*
         * We've reached the end of the information element - error.
         */
        goto past_end;
    }
    octet = tvb_get_guint8(tvb, offset);
    if (octet & Q931_IE_VL_EXTENSION) {
        /*
         * Only two octets long - error.
         */
        goto bad_length;
    }
    value |= (octet & 0x7F) << 7;
    offset += 1;
    len -= 1;
    value_len++;

    if (len == 0) {
        /*
         * We've reached the end of the information element - error.
         */
        goto past_end;
    }
    octet = tvb_get_guint8(tvb, offset);
    if (!(octet & Q931_IE_VL_EXTENSION)) {
        /*
         * More than three octets long - error.
         */
        goto bad_length;
    }
    value |= (octet & 0x7F);
    offset += 1;
    /*len -= 1;*/
    value_len++;

    proto_tree_add_uint_format_value(tree, hf_value, tvb, offset, value_len, value,
        "%u ms", value);
    return value_len;

past_end:
    expert_add_info_format(pinfo, item, &ei_q931_invalid_length,
        "%s goes past end of information element", proto_registrar_get_name(hf_value));
    return -1;

bad_length:
    expert_add_info_format(pinfo, item, &ei_q931_invalid_length, "%s isn't 3 octets long",
        proto_registrar_get_name(hf_value));
    return -1;
}

/*
 * Dissect an End-to-end transit delay information element.
 */
static void
dissect_q931_e2e_transit_delay_ie(tvbuff_t *tvb, packet_info *pinfo, int offset, int len,
    proto_tree *tree, proto_item* item)
{
    int value_len;

    if (len == 0)
        return;
    value_len = dissect_q931_guint16_value(tvb, pinfo, offset, len, tree, item, hf_q931_cumulative_transit_delay);
    if (value_len < 0)
        return; /* error */
    offset += value_len;
    len -= value_len;

    if (len == 0)
        return;
    value_len = dissect_q931_guint16_value(tvb, pinfo, offset, len, tree, item, hf_q931_requested_end_to_end_transit_delay);
    if (value_len < 0)
        return; /* error */
    offset += value_len;
    len -= value_len;

    if (len == 0)
        return;
    dissect_q931_guint16_value(tvb, pinfo, offset, len, tree, item, hf_q931_maximum_end_to_end_transit_delay);
}

/*
 * Dissect a Transit delay selection and indication information element.
 */
static void
dissect_q931_td_selection_and_int_ie(tvbuff_t *tvb, packet_info *pinfo, int offset, int len,
    proto_tree *tree, proto_item* item)
{
    if (len == 0)
        return;
    dissect_q931_guint16_value(tvb, pinfo, offset, len, tree, item, hf_q931_transit_delay);
}

/*
 * Dissect a Packet layer binary parameters information element.
 */
static const value_string q931_fast_selected_vals[] = {
    { 0x00, "Fast select not requested" },
    { 0x08, "Fast select not requested" },
    { 0x10, "Fast select requested with no restriction of response" },
    { 0x18, "Fast select requested with restrictions of response" },
    { 0x00, NULL }
};

static const true_false_string tfs_link_end = { "Link-by-link", "End-to-end" };
static const true_false_string tfs_pl_request = { "No request/request denied", "Request indicated/request accepted" };
static const true_false_string tfs_pl_modulus = { "8 sequencing", "128 sequencing" };

static void
dissect_q931_pl_binary_parameters_ie(tvbuff_t *tvb, int offset, int len,
    proto_tree *tree)
{
    const int * fields[] = {
        &hf_q931_fast_select,
        &hf_q931_pl_request,
        &hf_q931_pl_binary_confirmation,
        &hf_q931_pl_modulus,
        NULL
    };

    if (len == 0)
        return;

    proto_tree_add_bitmask_list(tree, tvb, offset, 1, fields, ENC_NA);
}

/*
 * Dissect a Packet layer window size information element.
 */
static void
dissect_q931_pl_window_size_ie(tvbuff_t *tvb, int offset, int len,
    proto_tree *tree)
{
    if (len == 0)
        return;
    proto_tree_add_item(tree, hf_q931_pl_window_size_forward_value, tvb, offset, 1, ENC_BIG_ENDIAN);
    offset += 1;
    len -= 1;

    if (len == 0)
        return;
    proto_tree_add_item(tree, hf_q931_pl_window_size_backward_value, tvb, offset, 1, ENC_BIG_ENDIAN);
}

/*
 * Dissect a Packet size information element.
 */
static void
dissect_q931_packet_size_ie(tvbuff_t *tvb, int offset, int len,
    proto_tree *tree)
{
    if (len == 0)
        return;
    proto_tree_add_item(tree, hf_q931_packet_size_forward_value, tvb, offset, 1, ENC_BIG_ENDIAN);
    offset += 1;
    len -= 1;

    if (len == 0)
        return;
    proto_tree_add_item(tree, hf_q931_packet_size_backward_value, tvb, offset, 1, ENC_BIG_ENDIAN);
}

/*
 * Dissect a Closed user group information element.
 */
static const value_string q931_cug_indication_vals[] = {
    { 0x01, "Closed user group selection" },
    { 0x02, "Closed user group with outgoing access selection and indication" },
    { 0,    NULL }
};

static void
dissect_q931_cug_ie(tvbuff_t *tvb, int offset, int len, proto_tree *tree)
{
    if (len == 0)
        return;
    proto_tree_add_item(tree, hf_q931_cug_indication, tvb, offset, 1, ENC_BIG_ENDIAN);
    offset += 1;
    len -= 1;

    if (len == 0)
        return;
    proto_tree_add_item(tree, hf_q931_cug_index_code, tvb, offset, len, ENC_NA|ENC_ASCII);
}

/*
 * Dissect a Reverse charging indication information element.
 */
static const value_string q931_reverse_charging_indication_vals[] = {
    { 0x01, "Reverse charging requested" },
    { 0,    NULL }
};

static void
dissect_q931_reverse_charge_ind_ie(tvbuff_t *tvb, int offset, int len,
    proto_tree *tree)
{
    if (len == 0)
        return;
    proto_tree_add_item(tree, hf_q931_reverse_charging_ind, tvb, offset, 1, ENC_BIG_ENDIAN);
}

/*
 * Dissect a (phone) number information element.
 */
static const value_string q931_number_type_vals[] = {
    { 0x0, "Unknown" },
    { 0x1, "International number" },
    { 0x2, "National number" },
    { 0x3, "Network specific number" },
    { 0x4, "Subscriber number" },
    { 0x6, "Abbreviated number" },
    { 0,    NULL }
};

static const value_string q931_numbering_plan_vals[] = {
    { 0x00, "Unknown" },
    { 0x01, "E.164 ISDN/telephony numbering" },
    { 0x03, "X.121 data numbering" },
    { 0x04, "F.69 Telex numbering" },
    { 0x08, "National standard numbering" },
    { 0x09, "Private numbering" },
    { 0,    NULL }
};

static const value_string q931_presentation_indicator_vals[] = {
    { 0x00, "Presentation allowed" },
    { 0x01, "Presentation restricted" },
    { 0x02, "Number not available due to interworking" },
    { 0,    NULL }
};

static const value_string q931_screening_indicator_vals[] = {
    { 0x00, "User-provided, not screened" },
    { 0x01, "User-provided, verified and passed" },
    { 0x02, "User-provided, verified and failed" },
    { 0x03, "Network-provided" },
    { 0,    NULL }
};

static const value_string q931_redirection_reason_vals[] = {
    { 0x00, "Unknown" },
    { 0x01, "Call forwarding busy or called DTE busy" },
    { 0x02, "Call forwarding no reply" },
    { 0x04, "Call deflection" },
    { 0x09, "Called DTE out of order" },
    { 0x0A, "Call forwarding by the called DTE" },
    { 0x0F, "Call forwarding unconditional or systematic call redirection" },
    { 0,    NULL }
};

static void
dissect_q931_number_ie(tvbuff_t *tvb, int offset, int len,
    proto_tree *tree, int hfindex, e164_info_t e164_info)
{
    guint8 octet;
    gint number_plan;

    if (len == 0)
        return;
    octet = tvb_get_guint8(tvb, offset);
    number_plan = octet & 0x0f;
    e164_info.nature_of_address = ( octet & 0x70 ) >> 4;
    proto_tree_add_uint(tree, hf_q931_numbering_plan, tvb, offset, 1, octet);
    proto_tree_add_uint(tree, hf_q931_number_type, tvb, offset, 1, octet);
    proto_tree_add_boolean(tree, hf_q931_extension_ind, tvb, offset, 1, octet);

    offset += 1;
    len -= 1;

    if (!(octet & Q931_IE_VL_EXTENSION)) {
        if (len == 0)
            return;
        octet = tvb_get_guint8(tvb, offset);
        proto_tree_add_uint(tree, hf_q931_screening_ind, tvb, offset, 1, octet);
        proto_tree_add_uint(tree, hf_q931_presentation_ind, tvb, offset, 1, octet);
        proto_tree_add_boolean(tree, hf_q931_extension_ind, tvb, offset, 1, octet);
        offset += 1;
        len -= 1;
    }

    /*
     * XXX - only in a Redirecting number information element.
     */
    if (!(octet & Q931_IE_VL_EXTENSION)) {
        if (len == 0)
            return;
        proto_tree_add_item(tree, hf_q931_extension_reason, tvb, offset, 1, ENC_BIG_ENDIAN);
        offset += 1;
        len -= 1;
    }

    if (len == 0)
        return;
    proto_tree_add_item(tree, hfindex, tvb, offset, len, ENC_ASCII|ENC_NA);
    proto_item_append_text(proto_tree_get_parent(tree), ": '%s'", tvb_format_text(tvb, offset, len));

    if ( number_plan == 1 ) {
        if ( e164_info.e164_number_type != NONE ){

            e164_info.E164_number_str = tvb_get_string_enc(wmem_packet_scope(), tvb, offset, len, ENC_ASCII|ENC_NA);
            e164_info.E164_number_length = len;
            dissect_e164_number(tvb, tree, offset, len, e164_info);
        }
    }

    /* Collect q931_packet_info */
    if ( e164_info.e164_number_type == CALLING_PARTY_NUMBER && have_valid_q931_pi)
        q931_pi->calling_number = tvb_get_string_enc(wmem_packet_scope(), tvb, offset, len, ENC_ASCII|ENC_NA);
    if ( e164_info.e164_number_type == CALLED_PARTY_NUMBER && have_valid_q931_pi)
        q931_pi->called_number = tvb_get_string_enc(wmem_packet_scope(), tvb, offset, len, ENC_ASCII|ENC_NA);
}

/*
 * Dissect a party subaddress information element.
 */
static const value_string q931_subaddress_type_vals[] = {
    { 0x00, "X.213/ISO 8348 Add.2 NSAP" },
    { 0x20, "User-specified" },
    { 0,    NULL }
};

static const value_string q931_odd_even_indicator_vals[] = {
    { 0x00, "Even number of address signals" },
    { 0x08, "Odd number of address signals" },
    { 0,    NULL }
};

static void
dissect_q931_party_subaddr_ie(tvbuff_t *tvb, int offset, int len,
    proto_tree *tree)
{
    if (len == 0)
        return;

    proto_tree_add_item(tree, hf_q931_party_subaddr_type, tvb, offset, 1, ENC_BIG_ENDIAN);
    proto_tree_add_item(tree, hf_q931_party_subaddr_odd_even_indicator, tvb, offset, 1, ENC_BIG_ENDIAN);
    offset += 1;
    len -= 1;

    if (len == 0)
        return;
    proto_tree_add_item(tree, hf_q931_party_subaddr, tvb, offset, len, ENC_NA);
}

/*
 * Dissect a Restart indicator information element.
 */
static const value_string q931_restart_indicator_class_vals[] = {
    { 0x00, "Indicated channels" },
    { 0x06, "Single interface" },
    { 0x07, "All interfaces" },
    { 0,    NULL }
};

static void
dissect_q931_restart_indicator_ie(tvbuff_t *tvb, packet_info *pinfo, int offset, int len,
    proto_tree *tree, proto_item* item)
{
    if (len != 1) {
        expert_add_info_format(pinfo, item, &ei_q931_invalid_length,
            "Restart indicator: length is %d, should be 1", len);
        return;
    }
    proto_tree_add_item(tree, hf_q931_restart_indicator, tvb, offset, 1, ENC_BIG_ENDIAN);
}

/*
 * Dissect a High-layer compatibility information element.
 */
#define Q931_MAINTENANCE    0x5e
#define Q931_MANAGEMENT     0x5f
#define Q931_AUDIOVISUAL    0x60
static const value_string q931_high_layer_characteristics_vals[] = {
    { 0x01,             "Telephony" },
    { 0x04,             "F.182 Facsimile Group 2/3" },
    { 0x21,             "F.184 Facsimile Group 4 Class I" },
    { 0x24,             "F.230 Teletex, basic and mixed mode, and F.184 Facsimile Group 4, Classes II and III" },
    { 0x28,             "F.220 Teletex, basic and processable mode" },
    { 0x31,             "F.200 Teletex, basic mode" },
    { 0x32,             "F.300 and T.102 syntax-based Videotex" },
    { 0x33,             "F.300 and T.101 international Videotex interworking" },
    { 0x35,             "F.60 Telex" },
    { 0x38,             "X.400 Message Handling Systems" },
    { 0x41,             "X.200 OSI application" },
    { 0x42,             "FTAM application" },
    { 0x5E,             "Reserved for maintenance" },
    { 0x5F,             "Reserved for management" },
    { Q931_AUDIOVISUAL, "F.720/F.821 and F.731 Profile 1a videotelephony" },
    { 0x61,             "F.702 and F.731 Profile 1b videoconferencing" },
    { 0x62,             "F.702 and F.731 audiographic conferencing" },
    { 0x68,             "F.700-series Multimedia services" },
    { 0,                NULL }
};
static value_string_ext q931_high_layer_characteristics_vals_ext = VALUE_STRING_EXT_INIT(q931_high_layer_characteristics_vals);

static const value_string q931_extended_high_layer_characteristics_vals[] = {
    { 0x01,             "Telephony" },
    { 0x04,             "F.182 Facsimile Group 2/3" },
    { 0x21,             "F.184 Facsimile Group 4 Class I" },
    { 0x24,             "F.230 Teletex, basic and mixed mode, and F.184 Facsimile Group 4, Classes II and III" },
    { 0x28,             "F.220 Teletex, basic and processable mode" },
    { 0x31,             "F.200 Teletex, basic mode" },
    { 0x32,             "F.300 and T.102 syntax-based Videotex" },
    { 0x33,             "F.300 and T.101 international Videotex interworking" },
    { 0x35,             "F.60 Telex" },
    { 0x38,             "X.400 Message Handling Systems" },
    { 0x41,             "X.200 OSI application" },
    { 0x42,             "FTAM application" },
    { 0x5E,             "Not available for assignment" },
    { 0x5F,             "Not available for assignment" },
    { Q931_AUDIOVISUAL, "F.720/F.821 and F.731 Profile 1a videotelephony" },
    { 0x61,             "F.702 and F.731 Profile 1b videoconferencing" },
    { 0x62,             "F.702 and F.731 audiographic conferencing" },
    { 0x68,             "F.700-series Multimedia services" },
    { 0,                NULL }
};
static value_string_ext q931_extended_high_layer_characteristics_vals_ext = VALUE_STRING_EXT_INIT(q931_extended_high_layer_characteristics_vals);

static const value_string q931_audiovisual_characteristics_vals[] = {
    { 0x01, "Capability set of initial channel of H.221" },
    { 0x02, "Capability set of subsequent channel of H.221" },
    { 0x21, "Capability set of initial channel of an active 3.1kHz audio or speech call" },
    { 0x00, NULL }
};

static const value_string q931_interpretation_vals[] = {
    { 0x04, "First (primary or only) high layer characteristics identification to be used in the call" },
    { 0x00, NULL }
};

static const value_string q931_pres_meth_prot_prof_vals[] = {
    { 0x01, "High layer protocol profile (without specification of attributes)" },
    { 0x00, NULL }
};

/*
 * High layer protocol profile
 */
#define Q931_HIGH_LAYER_PROTOCOL_PROFILE 0x01

void
dissect_q931_high_layer_compat_ie(tvbuff_t *tvb, int offset, int len,
    proto_tree *tree)
{
    guint8 octet;
    guint8 coding_standard;
    guint8 pres_method;
    guint8 characteristics;

    if (len == 0)
        return;
    octet = tvb_get_guint8(tvb, offset);
    coding_standard = octet & 0x60;
    pres_method = octet & 0x03;

    proto_tree_add_item(tree, hf_q931_extension_ind, tvb, offset, 1, ENC_BIG_ENDIAN);
    proto_tree_add_uint(tree, hf_q931_coding_standard, tvb, offset, 1, octet);
    proto_tree_add_uint(tree, hf_q931_interpretation, tvb, offset, 1, octet);
    proto_tree_add_uint(tree, hf_q931_pres_meth_prot_prof, tvb, offset, 1, octet);

    offset += 1;
    len -= 1;
    if ((coding_standard != Q931_ITU_STANDARDIZED_CODING) || (pres_method != Q931_HIGH_LAYER_PROTOCOL_PROFILE)) {
        /*
         * We don't know how the call state is encoded,
         * so just dump it as data and be done with it.
         */
        proto_tree_add_item(tree, hf_q931_high_layer_compat_data, tvb, offset, len, ENC_NA);
        return;
    }
    if (len == 0)
        return;

    octet = tvb_get_guint8(tvb, offset);
    characteristics = octet & 0x7F;

    proto_tree_add_item(tree, hf_q931_extension_ind, tvb, offset, 1, ENC_BIG_ENDIAN);
    proto_tree_add_uint(tree, hf_q931_high_layer_characteristics, tvb, offset, 1, octet);

    offset += 1;
    len -= 1;

    if (!(octet & Q931_IE_VL_EXTENSION)) {
        if (len == 0)
            return;
        octet = tvb_get_guint8(tvb, offset);
        if ((characteristics == Q931_AUDIOVISUAL) || (characteristics == 0x61) || (characteristics == 0x62) ||
            (characteristics == 0x68)) {
            proto_tree_add_item(tree, hf_q931_extension_ind, tvb, offset, 1, ENC_BIG_ENDIAN);
            proto_tree_add_uint(tree, hf_q931_extended_audiovisual_characteristics, tvb, offset, 1, octet);
        }
        else if ((characteristics == Q931_MANAGEMENT) || (characteristics == Q931_MAINTENANCE)) {
            proto_tree_add_item(tree, hf_q931_extension_ind, tvb, offset, 1, ENC_BIG_ENDIAN);
            proto_tree_add_uint(tree, hf_q931_extended_high_layer_characteristics, tvb, offset, 1, octet);
        }
    }
}


/*
 * Dissect a User-user information element.
 */
#define Q931_PROTOCOL_DISCRIMINATOR_USER    0x00
#define Q931_PROTOCOL_DISCRIMINATOR_IA5     0x04
#define Q931_PROTOCOL_DISCRIMINATOR_ASN1    0x05

static const value_string q931_protocol_discriminator_vals[] = {
    { Q931_PROTOCOL_DISCRIMINATOR_USER, "User-specific protocol" },
    { 0x01,                             "OSI high layer protocols" },
    { 0x02,                             "X.244" },
    { 0x03,                             "Reserved for system management convergence function" },
    { Q931_PROTOCOL_DISCRIMINATOR_IA5,  "IA5 characters" },
    { Q931_PROTOCOL_DISCRIMINATOR_ASN1, "X.208 and X.209 coded user information" },
    { 0x06,                             "Undefined" },
    { 0x07,                             "V.120 rate adaption" },
    { 0x08,                             "Q.931/I.451 user-network call control messages" },
    { 0,                                NULL }
};
value_string_ext q931_protocol_discriminator_vals_ext = VALUE_STRING_EXT_INIT(q931_protocol_discriminator_vals);

void
dissect_q931_user_user_ie(tvbuff_t *tvb, packet_info *pinfo, int offset, int len,
    proto_tree *tree)
{
    guint8 octet;
    tvbuff_t *next_tvb = NULL;
    heur_dtbl_entry_t *hdtbl_entry;

    if (len == 0)
        return;
    octet = tvb_get_guint8(tvb, offset);
    proto_tree_add_item(tree, hf_q931_user_protocol_discriminator, tvb, offset, 1, ENC_BIG_ENDIAN);
    offset += 1;
    len -= 1;

    if (len == 0)
        return;
    switch (octet) {

    case Q931_PROTOCOL_DISCRIMINATOR_USER:
        next_tvb = tvb_new_subset_length(tvb, offset, len);
        proto_tree_add_uint_format_value(tree, hf_q931_user_information_len, tvb, offset, len, len, "%d octets", len);
        if (!dissector_try_heuristic(q931_user_heur_subdissector_list, next_tvb, pinfo, tree, &hdtbl_entry, NULL)) {
        call_dissector_only(data_handle, next_tvb, pinfo, tree, NULL);
        }
        break;

    case Q931_PROTOCOL_DISCRIMINATOR_IA5:
        proto_tree_add_item(tree, hf_q931_user_information_str, tvb, offset, len, ENC_NA|ENC_ASCII);
        break;

    default:
        proto_tree_add_item(tree, hf_q931_user_information_bytes, tvb, offset, len, ENC_NA);
        break;
    }
}

static const value_string q931_party_category_vals[] = {
    { 0x00, "Unknown" },
    { 0x01, "Extension" },
    { 0x02, "Operator" },
    { 0x03, "Emergency extension" },
    { 0,    NULL }
};

static void
dissect_q931_party_category_ie(tvbuff_t *tvb, int offset, int len,
    proto_tree *tree)
{
    if (len == 0)
        return;

    proto_tree_add_item(tree, hf_q931_party_category, tvb, offset, 1, ENC_BIG_ENDIAN);
    /*offset += 1;
    len -= 1;

    if (len == 0)
        return;
    */
}

/*
 * Dissect information elements consisting of ASCII^H^H^H^H^HIA5 text.
 */
static void
dissect_q931_ia5_ie(tvbuff_t *tvb, int offset, int len, proto_tree *tree,
    int hf_value)
{
    if (len != 0) {
        proto_tree_add_item(tree, hf_value, tvb, offset, len, ENC_ASCII|ENC_NA);
        proto_item_append_text(proto_tree_get_parent(tree), "  '%s'", tvb_format_text(tvb, offset, len));
    }
}

static void
dissect_q931_pdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
    gboolean is_over_ip)
{
    int         offset = 0;
    proto_tree  *q931_tree = NULL;
    proto_tree  *ie_tree = NULL;
    proto_item  *ti;
    guint8      prot_discr;
    guint8      call_ref_len;
    guint8      call_ref[15];
    guint32     call_ref_val;
    guint8      message_type, segmented_message_type;
    guint8      info_element;
    guint16     info_element_len;
    gboolean    first_frag, more_frags;
    guint32     frag_len;
    fragment_head *fd_head;
    tvbuff_t *next_tvb = NULL;

    q931_pi=wmem_new(wmem_packet_scope(), q931_packet_info);

    /* Init struct for collecting q931_packet_info */
    reset_q931_packet_info(q931_pi);
    have_valid_q931_pi=TRUE;

    col_set_str(pinfo->cinfo, COL_PROTOCOL, "Q.931");

    prot_discr = tvb_get_guint8(tvb, offset);
    ti = proto_tree_add_item(tree, proto_q931, tvb, offset, -1, ENC_NA);
    if (tree) {
        q931_tree = proto_item_add_subtree(ti, ett_q931);

        dissect_q931_protocol_discriminator(tvb, offset, q931_tree);
    }
    offset += 1;
    call_ref_len = tvb_get_guint8(tvb, offset) & 0xF;   /* XXX - do as a bit field? */
    if (q931_tree != NULL)
        proto_tree_add_uint(q931_tree, hf_q931_call_ref_len, tvb, offset, 1, call_ref_len);
    offset += 1;
    switch (call_ref_len) {
        case 0: call_ref_val = 0; break;
        case 1: call_ref_val = tvb_get_guint8(tvb, offset); break;
        case 2: call_ref_val = tvb_get_ntohs(tvb, offset); break;
        case 3: call_ref_val = tvb_get_ntoh24(tvb, offset); break;
        default: call_ref_val = tvb_get_ntohl(tvb, offset);
    }
    if (call_ref_len != 0) {
        tvb_memcpy(tvb, call_ref, offset, call_ref_len);
        if (q931_tree != NULL) {
            proto_tree_add_boolean(q931_tree, hf_q931_call_ref_flag,
                tvb, offset, 1, (call_ref[0] & 0x80) != 0);
            call_ref[0] &= 0x7F;
            proto_tree_add_bytes(q931_tree, hf_q931_call_ref,
                tvb, offset, call_ref_len, call_ref);
        } else
        {       /* info for the tap */
            call_ref[0] &= 0x7F;
        }
        /* XXX - Should crv be something besides a guint32? */
        memcpy(&(q931_pi->crv), call_ref, call_ref_len > sizeof(q931_pi->crv) ? sizeof(q931_pi->crv) : call_ref_len );
        offset += call_ref_len;
    }
    message_type = tvb_get_guint8(tvb, offset);
    if(have_valid_q931_pi && q931_pi) {
        q931_pi->message_type = message_type;
    }
    col_add_str(pinfo->cinfo, COL_INFO, get_message_name(prot_discr, message_type));

    if (prot_discr == NLPID_DMS)
        proto_tree_add_item(q931_tree, hf_q931_maintenance_message_type, tvb, offset, 1, ENC_BIG_ENDIAN);
    else
        proto_tree_add_item(q931_tree, hf_q931_message_type, tvb, offset, 1, ENC_BIG_ENDIAN);

    offset += 1;

    /*
     * And now for the information elements....
     */
    if ((message_type != Q931_SEGMENT) || !q931_reassembly ||
            (tvb_reported_length_remaining(tvb, offset) <= 4)) {
        dissect_q931_IEs(tvb, pinfo, tree, q931_tree, is_over_ip, offset, 0);
        return;
    }
    info_element = tvb_get_guint8(tvb, offset);
    info_element_len = tvb_get_guint8(tvb, offset + 1);
    if ((info_element != Q931_IE_SEGMENTED_MESSAGE) || (info_element_len < 2)) {
        dissect_q931_IEs(tvb, pinfo, tree, q931_tree, is_over_ip, offset, 0);
        return;
    }
    /* Segmented message IE */
    ie_tree = proto_tree_add_subtree(q931_tree, tvb, offset, 1+1+info_element_len, ett_q931_ie[info_element], NULL,
                    val_to_str(info_element, q931_info_element_vals[0], "Unknown information element (0x%02X)"));
    proto_tree_add_uint_format_value(ie_tree, hf_q931_information_element, tvb, offset, 1, info_element,
                            "%s", val_to_str(info_element, q931_info_element_vals[0], "Unknown (0x%02X)"));
    proto_tree_add_item(ie_tree, hf_q931_information_element_len, tvb, offset + 1, 1, ENC_NA);
    dissect_q931_segmented_message_ie(tvb, pinfo, offset + 2, info_element_len, ie_tree, ti);
    first_frag = (tvb_get_guint8(tvb, offset + 2) & 0x80) != 0;
    more_frags = (tvb_get_guint8(tvb, offset + 2) & 0x7F) != 0;
    segmented_message_type = tvb_get_guint8(tvb, offset + 3);
    col_append_fstr(pinfo->cinfo, COL_INFO, " of %s",
            val_to_str_ext(segmented_message_type, &q931_message_type_vals_ext, "Unknown message type (0x%02X)"));

    offset += 1 + 1 + info_element_len;
    /* Reassembly */
    frag_len = tvb_reported_length_remaining(tvb, offset);
    if (first_frag && fragment_get(&q931_reassembly_table, pinfo, call_ref_val, NULL)) {
        /* there are some unreassembled segments, ignore them */
        fragment_end_seq_next(&q931_reassembly_table, pinfo, call_ref_val, NULL);
    }
    fd_head = fragment_add_seq_next(&q931_reassembly_table,
                    tvb, offset, pinfo, call_ref_val, NULL,
                    frag_len, more_frags);
    if (fd_head) {
        if (pinfo->fd->num == fd_head->reassembled_in) {  /* last fragment */
            if (fd_head->next != NULL) {  /* 2 or more segments */
                next_tvb = tvb_new_chain(tvb, fd_head->tvb_data);
                add_new_data_source(pinfo, next_tvb, "Reassembled Q.931 IEs");
                /* Show all fragments. */
                if (tree) {
                    proto_item *frag_tree_item;
                    show_fragment_seq_tree(fd_head, &q931_frag_items, q931_tree, pinfo, next_tvb, &frag_tree_item);
                }
            } else {  /* only 1 segment */
                next_tvb = tvb_new_subset_remaining(tvb, offset);
            }

            col_add_fstr(pinfo->cinfo, COL_INFO, "%s [reassembled]",
                    val_to_str_ext(segmented_message_type, &q931_message_type_vals_ext, "Unknown message type (0x%02X)"));

        } else {
            if (tree) proto_tree_add_uint(q931_tree, hf_q931_reassembled_in, tvb, offset, frag_len, fd_head->reassembled_in);
        }
    }
    if (next_tvb)
        dissect_q931_IEs(next_tvb, pinfo, tree, q931_tree, is_over_ip, 0, 0);
}

static const value_string q931_codeset_vals[] = {
    { 0x00, "Q.931 information elements" },
    { 0x04, "Information elements for ISO/IEC use" },
    { 0x05, "Information elements for national use" },
    { 0x06, "Information elements specific to the local network" },
    { 0x07, "User-specific information elements" },
    { 0x00, NULL },
};

static void
dissect_q931_IEs(tvbuff_t *tvb, packet_info *pinfo, proto_tree *root_tree,
    proto_tree *q931_tree, gboolean is_over_ip, int offset, int initial_codeset)
{
    proto_item  *ti;
    proto_tree  *ie_tree = NULL;
    guint8      info_element;
    guint8      dummy;
    guint16     info_element_len;
    int         codeset, locked_codeset;
    gboolean    non_locking_shift, first_segment;
    tvbuff_t    *h225_tvb, *next_tvb;
    e164_info_t e164_info;
    e164_info.e164_number_type = NONE;
    e164_info.nature_of_address = NONE;
    e164_info.E164_number_str = "";
    e164_info.E164_number_length = NONE;

    codeset = locked_codeset = initial_codeset;
    first_segment = FALSE;
    while (tvb_reported_length_remaining(tvb, offset) > 0) {
        info_element = tvb_get_guint8(tvb, offset);

        /* Check for the codeset shift */
        if ((info_element & Q931_IE_SO_MASK) &&
            ((info_element & Q931_IE_SO_IDENTIFIER_MASK) == Q931_IE_SHIFT)) {
            non_locking_shift = info_element & Q931_IE_SHIFT_NON_LOCKING;
            codeset = info_element & Q931_IE_SHIFT_CODESET;
            if (!non_locking_shift)
                locked_codeset = codeset;
            if (q931_tree != NULL) {
                proto_tree_add_uint_format(q931_tree, hf_q931_locking_codeset, tvb, offset, 1,
                    codeset, "%s shift to codeset %u: %s",
                    (non_locking_shift ? "Non-locking" : "Locking"),
                    codeset, val_to_str(codeset, q931_codeset_vals,
                      "Unknown (0x%02X)"));
            }
            offset += 1;
            continue;
        }

        /*
         * Check for the single-octet IEs.
         */
        if (info_element & Q931_IE_SO_MASK) {
            /*
             * Check for subdissectors for this IE or
             * for all IEs in this codeset.
             */
            if (dissector_get_uint_handle(codeset_dissector_table, codeset) ||
                dissector_get_uint_handle(ie_dissector_table, (codeset << 8) | (info_element & Q931_IE_SO_IDENTIFIER_MASK))) {
                next_tvb = tvb_new_subset_length (tvb, offset, 1);
                if (dissector_try_uint(ie_dissector_table, (codeset << 8) | (info_element & Q931_IE_SO_IDENTIFIER_MASK), next_tvb, pinfo, q931_tree) ||
                    dissector_try_uint(codeset_dissector_table, codeset, next_tvb, pinfo, q931_tree)) {
                    offset += 1;
                    codeset = locked_codeset;
                    continue;
                }
            }

            switch ((codeset << 8) | (info_element & Q931_IE_SO_IDENTIFIER_MASK)) {

            case CS0 | Q931_IE_MORE_DATA_OR_SEND_COMP:
                switch (info_element) {

                case Q931_IE_MORE_DATA:
                    proto_tree_add_item(q931_tree, hf_q931_more_data, tvb, offset, 1, ENC_NA);
                    break;

                case Q931_IE_SENDING_COMPLETE:
                    proto_tree_add_item(q931_tree, hf_q931_sending_complete, tvb, offset, 1, ENC_NA);
                    break;

                default:
                    proto_tree_add_expert_format(q931_tree, pinfo, &ei_q931_information_element, tvb, offset, 1,
                            "Unknown information element (0x%02X)", info_element);
                    break;
                }
                break;

            case CS0 | Q931_IE_CONGESTION_LEVEL:
                proto_tree_add_item(q931_tree, hf_q931_congestion_level, tvb, offset, 1, ENC_BIG_ENDIAN);
                break;

            case CS0 | Q931_IE_REPEAT_INDICATOR:
                proto_tree_add_item(q931_tree, hf_q931_repeat_indicator, tvb, offset, 1, ENC_BIG_ENDIAN);
                break;

            default:
                proto_tree_add_expert_format(q931_tree, pinfo, &ei_q931_information_element, tvb, offset, 1,
                        "Unknown information element (0x%02X)", info_element);
                break;
            }
            offset += 1;
            codeset = locked_codeset;
            continue;
        }

        /*
         * Variable-length IE.
         *
         * According to page 18 from Recommendation H.225.0 :
         * " Length of user-user contents contents
         * - Shall be 2 octets instead of 1 (as in Figure 4-36/Q.931)"
         *
         * We assume that if this is Q.931-over-TPKT, it might
         * be H.225 traffic, and check for the IE being a user-user
         * IE with ASN.1 encoding of the user information.
         */
        if (is_over_ip && tvb_bytes_exist(tvb, offset, 4) &&
            codeset == 0 && tvb_get_guint8(tvb, offset) == Q931_IE_USER_USER &&
            tvb_get_guint8(tvb, offset + 3) == Q931_PROTOCOL_DISCRIMINATOR_ASN1)  {
            info_element_len = tvb_get_ntohs(tvb, offset + 1);
            if (q931_tree != NULL) {
                ie_tree = proto_tree_add_subtree(q931_tree, tvb, offset,
                    1+2+info_element_len, ett_q931_ie[info_element], NULL,
                    val_to_str(info_element,
                      q931_info_element_vals[codeset],
                      "Unknown information element (0x%02X)"));
                proto_tree_add_uint_format_value(ie_tree, hf_q931_information_element, tvb, offset, 1, info_element, "%s", val_to_str(info_element,
                      q931_info_element_vals[codeset], "Unknown (0x%02X)"));
                proto_tree_add_item(ie_tree, hf_q931_information_element_len, tvb, offset + 1, 2, ENC_BIG_ENDIAN);
                proto_tree_add_item(ie_tree, hf_q931_user_protocol_discriminator, tvb, offset + 3, 1, ENC_NA);
            }

            if (info_element_len > 1) {
                /*
                 * If we don't desegment limit the length
                 * to the actual size in the frame
                 */
                if (!pinfo->can_desegment) {
                    info_element_len = MIN(info_element_len, tvb_captured_length_remaining(tvb, offset + 3));
                }
                /*
                 * Do we have a handle for the H.225
                 * dissector?
                 */
                if (h225_handle != NULL) {
                    /*
                     * Yes - call it, regardless of
                     * whether we're building a
                     * protocol tree or not.
                     */
                    h225_tvb = tvb_new_subset_length(tvb,
                        offset + 4, info_element_len - 1);
                    call_dissector(h225_handle, h225_tvb,
                        pinfo, root_tree);
                } else {
                    /*
                     * No - just show it as "User
                     * information" (if "ie_tree" is
                     * null, this won't add anything).
                     */
                    proto_tree_add_item(ie_tree, hf_q931_user_information_bytes, tvb, offset + 4, info_element_len - 1, ENC_NA);
                }
            }
            offset += 1 + 2 + info_element_len;
        } else {
            info_element_len = tvb_get_guint8(tvb, offset + 1);

            if (first_segment && (tvb_reported_length_remaining(tvb, offset + 2) < info_element_len)) {  /* incomplete IE at the end of the 1st segment */
                proto_tree_add_expert(q931_tree, pinfo, &ei_q931_incomplete_ie, tvb, offset, -1);
                break;
            }

            /*
             * Check for subdissectors for this IE or
             * for all IEs in this codeset.
             */
            if (dissector_get_uint_handle(codeset_dissector_table, codeset) ||
                dissector_get_uint_handle(ie_dissector_table, (codeset << 8) | info_element)) {
                next_tvb = tvb_new_subset_length (tvb, offset, info_element_len + 2);
                if (dissector_try_uint(ie_dissector_table, (codeset << 8) | info_element, next_tvb, pinfo, q931_tree) ||
                    dissector_try_uint(codeset_dissector_table, codeset, next_tvb, pinfo, q931_tree)) {
                    offset += 2 + info_element_len;
                    codeset = locked_codeset;
                    continue;
                }
            }

            ie_tree = proto_tree_add_subtree(q931_tree, tvb, offset, 1+1+info_element_len, ett_q931_ie[info_element], &ti,
                    val_to_str(info_element, q931_info_element_vals[codeset], "Unknown information element (0x%02X)"));
            proto_tree_add_uint_format_value(ie_tree, hf_q931_information_element, tvb, offset, 1, info_element, "%s",
                    val_to_str(info_element, q931_info_element_vals[codeset], "Unknown (0x%02X)"));
            proto_tree_add_uint(ie_tree, hf_q931_information_element_len, tvb, offset + 1, 1, info_element_len);

            if (((codeset << 8) | info_element) == (CS0 | Q931_IE_SEGMENTED_MESSAGE)) {
                dissect_q931_segmented_message_ie(tvb, pinfo, offset + 2, info_element_len, ie_tree, ti);
                col_append_fstr(pinfo->cinfo, COL_INFO, " of %s",
                        val_to_str_ext(tvb_get_guint8(tvb, offset + 3), &q931_message_type_vals_ext, "Unknown message type (0x%02X)"));

                if (tvb_get_guint8(tvb, offset + 2) & 0x80) {  /* the 1st segment */
                    first_segment = TRUE;
                } else {  /* not the 1st segment */
                    proto_tree_add_item(q931_tree, hf_q931_message_segment, tvb, offset + 4, -1, ENC_NA);
                    info_element_len += tvb_reported_length_remaining(tvb, offset + 4);
                }
            } else {
                /*
                 * For the calling number, called number,
                 * and release cause IEs, don't check
                 * for the tree being null, as
                 * the dissectors for those IEs also
                 * supply information for the tap used
                 * in VoIP calls.
                 */
                switch ((codeset << 8) | info_element) {

                case CS0 | Q931_IE_BEARER_CAPABILITY:
                case CS0 | Q931_IE_LOW_LAYER_COMPAT:
                    if (q931_tree != NULL) {
                        dissect_q931_bearer_capability_ie(tvb,
                            offset + 2, info_element_len,
                            ie_tree);
                    }
                    break;

                case CS0 | Q931_IE_CAUSE:
                    dissect_q931_cause_ie_unsafe(tvb,
                        offset + 2, info_element_len,
                        ie_tree,
                        hf_q931_cause_value, &dummy, q931_info_element_vals0);
                    break;

                case CS0 | Q931_IE_CHANGE_STATUS:
                    if (q931_tree != NULL) {
                        dissect_q931_change_status_ie(tvb,
                            offset + 2, info_element_len,
                            ie_tree);
                    }
                    break;

                case CS0 | Q931_IE_CALL_STATE:
                    if (q931_tree != NULL) {
                        dissect_q931_call_state_ie(tvb,
                            offset + 2, info_element_len,
                            ie_tree);
                    }
                    break;

                case CS0 | Q931_IE_CHANNEL_IDENTIFICATION:
                    if (q931_tree != NULL) {
                        dissect_q931_channel_identification_ie(
                            tvb, offset + 2, info_element_len,
                            ie_tree);
                    }
                    break;

                case CS0 | Q931_IE_PROGRESS_INDICATOR:
                    if (q931_tree != NULL) {
                        dissect_q931_progress_indicator_ie(tvb,
                            offset + 2, info_element_len,
                            ie_tree);
                    }
                    break;

                case CS0 | Q931_IE_NETWORK_SPECIFIC_FACIL:
                case CS0 | Q931_IE_TRANSIT_NETWORK_SEL:
                    if (q931_tree != NULL) {
                        dissect_q931_ns_facilities_ie(tvb,
                            offset + 2, info_element_len,
                            ie_tree);
                    }
                    break;

                case CS0 | Q931_IE_NOTIFICATION_INDICATOR:
                    if (q931_tree != NULL) {
                        dissect_q931_notification_indicator_ie(
                            tvb, offset + 2, info_element_len,
                            ie_tree);
                    }
                    break;

                case CS0 | Q931_IE_DISPLAY:
                    if (q931_tree != NULL) {
                        dissect_q931_ia5_ie(tvb, offset + 2, info_element_len, ie_tree, hf_q931_display_information);
                    }
                    break;

                case CS0 | Q931_IE_DATE_TIME:
                    dissect_q931_date_time_ie(tvb, pinfo,
                            offset + 2, info_element_len,
                            ie_tree);
                    break;

                case CS0 | Q931_IE_KEYPAD_FACILITY:
                    if (q931_tree != NULL) {
                        dissect_q931_ia5_ie(tvb, offset + 2, info_element_len, ie_tree, hf_q931_keypad_facility);
                    }
                    break;

                case CS0 | Q931_IE_SIGNAL:
                    dissect_q931_signal_ie(tvb, pinfo,
                            offset + 2, info_element_len,
                            ie_tree, ti);
                    break;

                case CS0 | Q931_IE_INFORMATION_RATE:
                    dissect_q931_information_rate_ie(tvb, pinfo,
                            offset + 2, info_element_len,
                            ie_tree, ti);
                    break;

                case CS0 | Q931_IE_E2E_TRANSIT_DELAY:
                    dissect_q931_e2e_transit_delay_ie(tvb, pinfo,
                            offset + 2, info_element_len,
                            ie_tree, ti);
                    break;

                case CS0 | Q931_IE_TD_SELECTION_AND_INT:
                    dissect_q931_td_selection_and_int_ie(
                            tvb, pinfo, offset + 2, info_element_len,
                            ie_tree, ti);
                    break;

                case CS0 | Q931_IE_PL_BINARY_PARAMETERS:
                    if (q931_tree != NULL) {
                        dissect_q931_pl_binary_parameters_ie(
                            tvb, offset + 2, info_element_len,
                            ie_tree);
                    }
                    break;

                case CS0 | Q931_IE_PL_WINDOW_SIZE:
                    if (q931_tree != NULL) {
                        dissect_q931_pl_window_size_ie(tvb,
                            offset + 2, info_element_len,
                            ie_tree);
                    }
                    break;

                case CS0 | Q931_IE_PACKET_SIZE:
                    if (q931_tree != NULL) {
                        dissect_q931_packet_size_ie(tvb,
                            offset + 2, info_element_len,
                            ie_tree);
                    }
                    break;

                case CS0 | Q931_IE_CUG:
                    if (q931_tree != NULL) {
                        dissect_q931_cug_ie(tvb,
                            offset + 2, info_element_len,
                            ie_tree);
                    }
                    break;

                case CS0 | Q931_IE_REVERSE_CHARGE_IND:
                    if (q931_tree != NULL) {
                        dissect_q931_reverse_charge_ind_ie(tvb,
                            offset + 2, info_element_len,
                            ie_tree);
                    }
                    break;

                case CS0 | Q931_IE_CONNECTED_NUMBER_DEFAULT:
                    if (q931_tree != NULL) {
                        dissect_q931_number_ie(tvb,
                            offset + 2, info_element_len,
                            ie_tree,
                            hf_q931_connected_number, e164_info);
                    }
                    break;


                case CS0 | Q931_IE_CALLING_PARTY_NUMBER:
                    e164_info.e164_number_type = CALLING_PARTY_NUMBER;
                    dissect_q931_number_ie(tvb,
                        offset + 2, info_element_len,
                        ie_tree,
                        hf_q931_calling_party_number, e164_info);
                    break;

                case CS0 | Q931_IE_CALLED_PARTY_NUMBER:
                    e164_info.e164_number_type = CALLED_PARTY_NUMBER;
                    dissect_q931_number_ie(tvb,
                        offset + 2, info_element_len,
                        ie_tree,
                        hf_q931_called_party_number, e164_info);
                    break;

                case CS0 | Q931_IE_CALLING_PARTY_SUBADDR:
                case CS0 | Q931_IE_CALLED_PARTY_SUBADDR:
                    if (q931_tree != NULL) {
                        dissect_q931_party_subaddr_ie(tvb,
                            offset + 2, info_element_len,
                            ie_tree);
                    }
                    break;

                case CS0 | Q931_IE_REDIRECTING_NUMBER:
                    if (q931_tree != NULL) {
                        dissect_q931_number_ie(tvb,
                            offset + 2, info_element_len,
                            ie_tree,
                            hf_q931_redirecting_number, e164_info);
                    }
                    break;

                case CS0 | Q931_IE_RESTART_INDICATOR:
                    dissect_q931_restart_indicator_ie(tvb, pinfo,
                            offset + 2, info_element_len,
                            ie_tree, ti);
                    break;

                case CS0 | Q931_IE_HIGH_LAYER_COMPAT:
                    if (q931_tree != NULL) {
                        dissect_q931_high_layer_compat_ie(tvb,
                            offset + 2, info_element_len,
                            ie_tree);
                    }
                    break;

                case CS0 | Q931_IE_USER_USER:
                    if (q931_tree != NULL) {
                        dissect_q931_user_user_ie(tvb, pinfo,
                            offset + 2, info_element_len,
                            ie_tree);
                    }
                    break;

                case CS5 | Q931_IE_PARTY_CATEGORY:
                    if (q931_tree != NULL) {
                        dissect_q931_party_category_ie(tvb,
                            offset + 2, info_element_len,
                            ie_tree);
                    }
                    break;

                case CS6 | Q931_IE_DISPLAY:
                    if (q931_tree != NULL) {
                        dissect_q931_ia5_ie(tvb, offset + 2, info_element_len, ie_tree, hf_q931_avaya_display);
                    }
                    break;

                default:
                    if (q931_tree != NULL) {
                        proto_tree_add_item(ie_tree, hf_q931_data, tvb,
                            offset + 2, info_element_len, ENC_NA);
                    }
                    break;
                }
            }
            offset += 1 + 1 + info_element_len;
        }
        codeset = locked_codeset;
    }
    if(have_valid_q931_pi) {
        tap_queue_packet(q931_tap, pinfo, q931_pi);
    }
    have_valid_q931_pi=FALSE;
}

/*
 * Q.931-over-TPKT-over-TCP.
 */
static gboolean
dissect_q931_tpkt_heur(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{
    int lv_tpkt_len;

    /*
     * Check whether this looks like a TPKT-encapsulated
     * Q.931 packet.
     *
     * The minimum length of a Q.931 message is 3:
     * 1 byte for the protocol discriminator,
     * 1 for the call_reference length,
     * and one for the message type.
     */
    lv_tpkt_len = is_tpkt(tvb, 3);
    if (lv_tpkt_len == -1) {
        /*
         * It's not a TPKT packet; reject it.
         */
        return FALSE;
    }

    /*
     * If this segment is *exactly* the length of a TPKT header,
     * we assume that, as it looks like a TPKT header, it
     * is one, and that the code put a TPKT header in one
     * segment and the rest of the PDU in another.
     */
    if (tvb_reported_length(tvb) == 4) {
        /*
         * It is - call the "dissect TPKT over a TCP stream"
         * routine.
         */
        dissect_tpkt_encap(tvb, pinfo, tree, q931_desegment,
            q931_tpkt_pdu_handle);
        return TRUE;
    }

    /*
     * Well, we have more data than just the TPKT header;
     * check whether it looks like the beginning of a
     * Q.931 message.
     *
     * The minimum length of a Q.931 message is 3, as per the
     * above.
     *
     * Check that we have that many bytes past the TPKT header in
     * the tvbuff; we already know that the TPKT header says we
     * have that many bytes (as we passed 3 as the "min_len" argument
     * to "is_tpkt()").
     */
    if (!tvb_bytes_exist(tvb, 4, 3))
        return FALSE;

    /* Check the protocol discriminator */
    if ((tvb_get_guint8(tvb, 4) != NLPID_Q_931) && (tvb_get_guint8(tvb, 4) != 0x03)) {
        /* Doesn't look like Q.931 inside TPKT */
        return FALSE;
    }

    /*
     * OK, it looks like Q.931-over-TPKT.
     * Call the "dissect TPKT over a TCP stream" routine.
     */
    dissect_tpkt_encap(tvb, pinfo, tree, q931_desegment,
        q931_tpkt_pdu_handle);

    return TRUE;
}

static int
dissect_q931_tpkt(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
    dissect_q931_tpkt_heur(tvb, pinfo, tree, NULL);
    return tvb_captured_length(tvb);
}

static int
dissect_q931_tpkt_pdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
    dissect_q931_pdu(tvb, pinfo, tree, TRUE);
    return tvb_captured_length(tvb);
}

static int
dissect_q931(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
    dissect_q931_pdu(tvb, pinfo, tree, FALSE);
    return tvb_captured_length(tvb);
}

static int
dissect_q931_over_ip(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
    dissect_q931_pdu(tvb, pinfo, tree, TRUE);
	return tvb_captured_length(tvb);
}

static int
dissect_q931_ie_cs0(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
    dissect_q931_IEs(tvb, pinfo, NULL, tree, FALSE, 0, 0);
    return tvb_captured_length(tvb);
}

static int
dissect_q931_ie_cs7(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
    dissect_q931_IEs(tvb, pinfo, NULL, tree, FALSE, 0, 7);
    return tvb_captured_length(tvb);
}

static void
q931_init(void) {
    reassembly_table_init(&q931_reassembly_table,
                &addresses_reassembly_table_functions);
}

static void
q931_cleanup(void) {
    reassembly_table_destroy(&q931_reassembly_table);
}

void
proto_register_q931(void)
{
    guint i;
    guint last_offset;

    static hf_register_info hf[] = {
        { &hf_q931_discriminator,
          { "Protocol discriminator", "q931.disc", FT_UINT8, BASE_HEX, NULL, 0x0,
            NULL, HFILL }},

        { &hf_q931_call_ref_len,
          { "Call reference value length", "q931.call_ref_len", FT_UINT8, BASE_DEC, NULL, 0x0,
            NULL, HFILL }},

        { &hf_q931_call_ref_flag,
          { "Call reference flag", "q931.call_ref_flag", FT_BOOLEAN, BASE_NONE, TFS(&tfs_call_ref_flag), 0x0,
            NULL, HFILL }},

        { &hf_q931_call_ref,
          { "Call reference value", "q931.call_ref", FT_BYTES, BASE_NONE, NULL, 0x0,
            NULL, HFILL }},

        { &hf_q931_message_type,
          { "Message type", "q931.message_type", FT_UINT8, BASE_HEX|BASE_EXT_STRING, &q931_message_type_vals_ext, 0x0,
            NULL, HFILL }},

        { &hf_q931_maintenance_message_type,
          { "Maintenance message type", "q931.maintenance_message_type", FT_UINT8, BASE_HEX, VALS(dms_message_type_vals), 0x0,
            NULL, HFILL }},

        { &hf_q931_segment_type,
          { "Segmented message type", "q931.segment_type", FT_UINT8, BASE_HEX|BASE_EXT_STRING, &q931_message_type_vals_ext, 0x0,
            NULL, HFILL }},

        { &hf_q931_coding_standard,
          { "Coding standard", "q931.coding_standard", FT_UINT8, BASE_HEX,
             VALS(q931_coding_standard_vals), 0x60,NULL, HFILL }},

        { &hf_q931_interpretation,
          { "Interpretation", "q931.interpretation", FT_UINT8, BASE_HEX,
            VALS(q931_interpretation_vals), 0x1C, NULL, HFILL}},

        { &hf_q931_pres_meth_prot_prof,
          { "Presentation method of protocol profile", "q931.presentation_method_protocol_profile", FT_UINT8, BASE_HEX,
            VALS(q931_pres_meth_prot_prof_vals), 0x03, NULL, HFILL}},

        { &hf_q931_high_layer_characteristics,
          { "High layer characteristics identification", "q931.high_layer_characteristics", FT_UINT8, BASE_HEX|BASE_EXT_STRING,
            &q931_high_layer_characteristics_vals_ext, 0x7f, NULL, HFILL }},

        { &hf_q931_extended_high_layer_characteristics,
          { "Extended high layer characteristics identification", "q931.extended_high_layer_characteristics", FT_UINT8, BASE_HEX|BASE_EXT_STRING,
            &q931_extended_high_layer_characteristics_vals_ext, 0x7f, NULL, HFILL }},

        { &hf_q931_extended_audiovisual_characteristics,
          { "Extended audiovisual characteristics identification", "q931.extended_audiovisual_characteristics", FT_UINT8, BASE_HEX,
            VALS(q931_audiovisual_characteristics_vals), 0x7f, NULL, HFILL }},

        { &hf_q931_information_transfer_capability,
          { "Information transfer capability", "q931.information_transfer_capability", FT_UINT8, BASE_HEX,
             VALS(q931_information_transfer_capability_vals), 0x1f,NULL, HFILL }},

        { &hf_q931_transfer_mode,
          { "Transfer mode", "q931.transfer_mode", FT_UINT8, BASE_HEX,
             VALS(q931_transfer_mode_vals), 0x60,NULL, HFILL }},

        { &hf_q931_information_transfer_rate,
          { "Information transfer rate", "q931.information_transfer_rate", FT_UINT8, BASE_HEX,
             VALS(q931_information_transfer_rate_vals), 0x1f,NULL, HFILL }},

        { &hf_q931_layer_ident,
          { "Layer identification", "q931.layer_ident", FT_UINT8, BASE_HEX,
             VALS(q931_bearer_capability_layer_ident_vals), 0x60, NULL, HFILL }},

        { &hf_q931_uil1,
          { "User information layer 1 protocol", "q931.uil1", FT_UINT8, BASE_HEX|BASE_EXT_STRING,
             &q931_uil1_vals_ext, 0x1f,NULL, HFILL }},

        { &hf_q931_cause_location,
          { "Cause location", "q931.cause_location", FT_UINT8, BASE_DEC|BASE_EXT_STRING, &q931_cause_location_vals_ext, 0x0f,
            NULL, HFILL }},

        { &hf_q931_cause_value,
          { "Cause value", "q931.cause_value", FT_UINT8, BASE_DEC|BASE_EXT_STRING, &q931_cause_code_vals_ext, 0x7f,
            NULL, HFILL }},

        { &hf_q931_number_type,
          { "Number type", "q931.number_type", FT_UINT8, BASE_HEX, VALS(q931_number_type_vals), 0x70,
            NULL, HFILL }},

        { &hf_q931_numbering_plan,
          { "Numbering plan", "q931.numbering_plan", FT_UINT8, BASE_HEX, VALS(q931_numbering_plan_vals), 0x0f,
            NULL, HFILL }},

        { &hf_q931_screening_ind,
          { "Screening indicator", "q931.screening_ind", FT_UINT8, BASE_HEX, VALS(q931_screening_indicator_vals), 0x03,
            NULL, HFILL }},

        { &hf_q931_presentation_ind,
          { "Presentation indicator", "q931.presentation_ind", FT_UINT8, BASE_HEX, VALS(q931_presentation_indicator_vals), 0x60,
            NULL, HFILL }},

        { &hf_q931_extension_ind,
          { "Extension indicator",  "q931.extension_ind",
            FT_BOOLEAN, 8, TFS(&q931_extension_ind_value), 0x80,
            NULL, HFILL }},

        { &hf_q931_extension_ind_preference,
          { "Preference",  "q931.extension_ind_preference",
            FT_UINT8, BASE_DEC, VALS(q931_status_preference_vals), 0x40,
            NULL, HFILL }},

        { &hf_q931_extension_ind_new_status,
          { "New status",  "q931.extension_ind_new_status",
            FT_UINT8, BASE_DEC, VALS(q931_new_status_vals), 0x07,
            NULL, HFILL }},

        { &hf_q931_calling_party_number,
          { "Calling party number digits", "q931.calling_party_number.digits", FT_STRING, BASE_NONE, NULL, 0x0,
            NULL, HFILL }},

        { &hf_q931_called_party_number,
          { "Called party number digits", "q931.called_party_number.digits", FT_STRING, BASE_NONE, NULL, 0x0,
            NULL, HFILL }},

        { &hf_q931_connected_number,
          { "Connected party number digits", "q931.connected_number.digits", FT_STRING, BASE_NONE, NULL, 0x0,
            NULL, HFILL }},

        { &hf_q931_redirecting_number,
          { "Redirecting party number digits", "q931.redirecting_number.digits", FT_STRING, BASE_NONE, NULL, 0x0,
            NULL, HFILL }},

        /* fields for channel identification IE */
        /* 0x80 is the extension bit */

        { &hf_q931_channel_interface_explicit,
          { "Interface identifier present", "q931.channel.interface_id_present", FT_BOOLEAN, 8, NULL, 0x40,
            "True if the interface identifier is explicit in the following octets", HFILL }},

        { &hf_q931_channel_interface_type,
          { "Interface type", "q931.channel.interface_type", FT_BOOLEAN, 8, TFS(&tfs_interface_type), 0x20,
            "Identifies the ISDN interface type", HFILL }},

        /* 0x10 is spare */

        { &hf_q931_channel_exclusive,
          { "Indicated channel", "q931.channel.exclusive", FT_BOOLEAN, 8, TFS(&tfs_channel_exclusive), 0x08,
            "True if only the indicated channel is acceptable", HFILL }},

        { &hf_q931_channel_dchan,
          { "D-channel indicator", "q931.channel.dchan", FT_BOOLEAN, 8, NULL, 0x04,
            "True if the identified channel is the D-Channel", HFILL }},

        { &hf_q931_channel_selection_bri,
          { "Information channel selection", "q931.channel.selection", FT_UINT8, BASE_HEX, VALS(q931_basic_channel_selection_vals), 0x03,
            "Identifies the information channel to be used", HFILL }},

        { &hf_q931_channel_selection_pri,
          { "Information channel selection", "q931.channel.selection", FT_UINT8, BASE_HEX, VALS(q931_not_basic_channel_selection_vals), 0x03,
            "Identifies the information channel to be used", HFILL }},

        { &hf_q931_channel_map,
          { "Number/map", "q931.channel.map", FT_BOOLEAN, 8, TFS(&tfs_channel_map), 0x10,
            "True if channel is indicates by channel map rather than number", HFILL }},

        { &hf_q931_channel_element_type,
          { "Element type", "q931.channel.element_type", FT_UINT8, BASE_HEX, VALS(q931_element_type_vals), 0xF,
            "Type of element in the channel number/slot map octets", HFILL }},

        { &hf_q931_channel_number,
          { "Channel number", "q931.channel.number", FT_UINT8, BASE_DEC, NULL, 0x7F,
            NULL, HFILL }},

        /* desegmentation fields */
        { &hf_q931_segment_overlap,
          { "Segment overlap", "q931.segment.overlap", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
            "Fragment overlaps with other fragments", HFILL }},

        { &hf_q931_segment_overlap_conflict,
          { "Conflicting data in fragment overlap", "q931.segment.overlap.conflict", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
            "Overlapping fragments contained conflicting data", HFILL }},

        { &hf_q931_segment_multiple_tails,
          { "Multiple tail fragments found", "q931.segment.multipletails", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
            "Several tails were found when defragmenting the packet", HFILL }},

        { &hf_q931_segment_too_long_segment,
          { "Segment too long", "q931.segment.toolongfragment", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
            "Segment contained data past end of packet", HFILL }},

        { &hf_q931_segment_error,
          { "Defragmentation error", "q931.segment.error", FT_FRAMENUM, BASE_NONE, NULL, 0x0,
            "Defragmentation error due to illegal fragments", HFILL }},

        { &hf_q931_segment_count,
          { "Segment count", "q931.segment.count", FT_UINT32, BASE_DEC, NULL, 0x0,
            NULL, HFILL}},

        { &hf_q931_segment,
          { "Q.931 Segment", "q931.segment", FT_FRAMENUM, BASE_NONE, NULL, 0x0,
            NULL, HFILL }},

        { &hf_q931_segments,
          { "Q.931 Segments", "q931.segments", FT_NONE, BASE_NONE, NULL, 0x0,
            NULL, HFILL }},

        { &hf_q931_reassembled_in,
          { "Reassembled Q.931 in frame", "q931.reassembled_in", FT_FRAMENUM, BASE_NONE, NULL, 0x0,
            "This Q.931 message is reassembled in this frame", HFILL}},

        { &hf_q931_reassembled_length,
          { "Reassembled Q.931 length", "q931.reassembled.length", FT_UINT32, BASE_DEC, NULL, 0x0,
            "The total length of the reassembled payload", HFILL}},

        /* Generated from convert_proto_tree_add_text.pl */
        { &hf_q931_first_segment,
          { "First segment", "q931.segment.first",
            FT_UINT8, BASE_DEC, NULL, 0x7F,
            NULL, HFILL }
        },
        { &hf_q931_not_first_segment,
          { "Not first segment", "q931.segment.not_first",
            FT_UINT8, BASE_DEC, NULL, 0x7F,
            NULL, HFILL }
        },
        { &hf_q931_bearer_capability_data,
          { "Data", "q931.bearer_capability.data",
            FT_BYTES, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_bearer_capability_rate_multiplier,
          { "Rate multiplier", "q931.bearer_capability.rate_multiplier",
            FT_UINT8, BASE_DEC, NULL, 0x7f,
            NULL, HFILL }
        },
        { &hf_q931_bearer_capability_user_rate,
          { "User rate", "q931.bearer_capability.user_rate",
            FT_UINT8, BASE_HEX|BASE_EXT_STRING, &q931_l1_user_rate_vals_ext, 0x1F,
            NULL, HFILL }
        },
        { &hf_q931_bearer_capability_intermediate_rate,
          { "Intermediate rate", "q931.bearer_capability.intermediate_rate",
            FT_UINT8, BASE_HEX, VALS(q931_l1_intermediate_rate_vals), 0x60,
            NULL, HFILL }
        },
        { &hf_q931_bearer_capability_stop_bits,
          { "Stop bits", "q931.bearer_capability.stop_bits",
            FT_UINT8, BASE_HEX, VALS(q931_l1_stop_bits_vals), 0x60,
            NULL, HFILL }
        },
        { &hf_q931_bearer_capability_data_bits,
          { "Data bits", "q931.bearer_capability.data_bits",
            FT_UINT8, BASE_HEX, VALS(q931_l1_data_bits_vals), 0x18,
            NULL, HFILL }
        },
        { &hf_q931_bearer_capability_parity,
          { "Parity", "q931.bearer_capability.parity",
            FT_UINT8, BASE_HEX, VALS(q931_l1_parity_vals), 0x07,
            NULL, HFILL }
        },
        { &hf_q931_bearer_capability_modem_type,
          { "Modem type", "q931.bearer_capability.modem_type",
            FT_UINT8, BASE_HEX|BASE_RANGE_STRING, RVALS(q931_l1_modem_type_rvals), 0x3F,
            NULL, HFILL }
        },
        { &hf_q931_uil2,
          { "User information layer 2 protocol", "q931.uil2",
            FT_UINT8, BASE_HEX|BASE_EXT_STRING, &q931_uil2_vals_ext, 0x1F,
            NULL, HFILL }
        },
        { &hf_q931_uil2_info,
          { "User-specified layer 2 protocol information", "q931.uil2_info",
            FT_UINT8, BASE_HEX, NULL, 0x7F,
            NULL, HFILL }
        },
        { &hf_q931_bearer_capability_mode,
          { "Mode", "q931.bearer_capability.mode",
            FT_UINT8, BASE_HEX, VALS(q931_mode_vals), 0x60,
            NULL, HFILL }
        },
        { &hf_q931_bearer_capability_window_size,
          { "Window size", "q931.bearer_capability.window_size",
            FT_UINT8, BASE_DEC, NULL, 0x7F,
            NULL, HFILL }
        },
        { &hf_q931_uil3,
          { "User information layer 3 protocol", "q931.uil3",
            FT_UINT8, BASE_HEX, VALS(q931_uil3_vals), 0x1F,
            NULL, HFILL }
        },
        { &hf_q931_bearer_capability_default_packet_size,
          { "Default packet size", "q931.bearer_capability.default_packet_size",
            FT_UINT8, BASE_DEC, NULL, 0x0F,
            NULL, HFILL }
        },
        { &hf_q931_bearer_capability_packet_window_size,
          { "Packet window size", "q931.bearer_capability.packet_window_size",
            FT_UINT8, BASE_DEC, NULL, 0x7F,
            NULL, HFILL }
        },
        { &hf_q931_uil3_additional,
          { "Additional layer 3 protocol information", "q931.uil3_additional",
            FT_UINT16, BASE_HEX, VALS(nlpid_vals), 0x0,
            NULL, HFILL }
        },
        { &hf_q931_cause_data,
          { "Data", "q931.cause.data",
            FT_BYTES, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_cause_recommendation,
          { "Recommendation", "q931.cause.recommendation",
            FT_UINT8, BASE_HEX, VALS(q931_cause_recommendation_vals), 0x7F,
            NULL, HFILL }
        },
        { &hf_q931_cause_call_rejection_reason,
          { "Rejection reason", "q931.cause_call.rejection_reason",
            FT_UINT8, BASE_HEX, VALS(q931_rejection_reason_vals), 0x7C,
            NULL, HFILL }
        },
        { &hf_q931_cause_call_condition,
          { "Condition", "q931.cause_call.condition",
            FT_UINT8, BASE_HEX, VALS(q931_cause_condition_vals), 0x03,
            NULL, HFILL }
        },
        { &hf_q931_cause_call_user_specific_diagnostic,
          { "User specific diagnostic", "q931.cause_call.user_specific_diagnostic",
            FT_BYTES, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_cause_call_diagnostic,
          { "Diagnostic", "q931.cause_call.diagnostic",
            FT_BYTES, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_cause_call_message_type,
          { "Message type", "q931.cause_call.message_type",
            FT_UINT8, BASE_HEX|BASE_EXT_STRING, &q931_message_type_vals_ext, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_cause_call_rec_timer,
          { "Timer", "q931.cause_call.rec_timer",
            FT_STRING, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_call_state_data,
          { "Data", "q931.call_state.data",
            FT_BYTES, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_call_state,
          { "Call state", "q931.call_state",
            FT_UINT8, BASE_HEX|BASE_EXT_STRING, &q931_call_state_vals_ext, 0x3F,
            NULL, HFILL }
        },
        { &hf_q931_channel_interface_id,
          { "Interface ID", "q931.channel.interface_id",
            FT_UINT32, BASE_DEC, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_channel_data,
          { "Data", "q931.channel.data",
            FT_BYTES, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_channel_slot_map,
          { "Slot map", "q931.channel.slot_map",
            FT_UINT8, BASE_HEX, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_progress_indicator_data,
          { "Data", "q931.progress_indicator.data",
            FT_BYTES, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_progress_indicator_location,
          { "Location", "q931.progress_indicator.location",
            FT_UINT8, BASE_HEX|BASE_EXT_STRING, &q931_cause_location_vals_ext, 0x0F,
            NULL, HFILL }
        },
        { &hf_q931_progress_indicator_description,
          { "Progress description", "q931.progress_indicator.description",
            FT_UINT8, BASE_HEX|BASE_EXT_STRING, &q931_progress_description_vals_ext, 0x7F,
            NULL, HFILL }
        },
        { &hf_q931_netid_length,
          { "Network identification length", "q931.netid.length",
            FT_UINT8, BASE_DEC, NULL, 0x7F,
            NULL, HFILL }
        },
        { &hf_q931_netid_type,
          { "Type of network identification", "q931.netid.type",
            FT_UINT8, BASE_HEX, VALS(q931_netid_type_vals), 0x70,
            NULL, HFILL }
        },
        { &hf_q931_netid_plan,
          { "Network identification plan", "q931.netid.plan",
            FT_UINT8, BASE_HEX, VALS(q931_netid_plan_vals), 0x0F,
            NULL, HFILL }
        },
        { &hf_q931_netid,
          { "Network identification", "q931.netid",
            FT_STRING, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_netid_facility_specification,
          { "Network-specific facility specification", "q931.netid.facility_specification",
            FT_BYTES, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_notification_description,
          { "Notification description", "q931.notification_description",
            FT_UINT8, BASE_HEX, VALS(q931_notification_description_vals), 0x7F,
            NULL, HFILL }
        },
        { &hf_q931_signal,
          { "Signal", "q931.signal",
            FT_UINT8, BASE_HEX|BASE_EXT_STRING, &q931_signal_vals_ext, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_information_rate_incoming,
          { "Incoming information rate", "q931.information_rate.incoming",
            FT_UINT8, BASE_HEX|BASE_EXT_STRING, &q931_throughput_class_vals_ext, 0x1F,
            NULL, HFILL }
        },
        { &hf_q931_information_rate_outgoing,
          { "Outgoing information rate", "q931.information_rate.outgoing",
            FT_UINT8, BASE_HEX|BASE_EXT_STRING, &q931_throughput_class_vals_ext, 0x1F,
            NULL, HFILL }
        },
        { &hf_q931_information_rate_minimum_incoming,
          { "Minimum incoming information rate", "q931.information_rate.minimum_incoming",
            FT_UINT8, BASE_HEX|BASE_EXT_STRING, &q931_throughput_class_vals_ext, 0x1F,
            NULL, HFILL }
        },
        { &hf_q931_information_rate_minimum_outgoing,
          { "Minimum outgoing information rate", "q931.information_rate.minimum_outgoing",
            FT_UINT8, BASE_HEX|BASE_EXT_STRING, &q931_throughput_class_vals_ext, 0x1F,
            NULL, HFILL }
        },
        { &hf_q931_fast_select,
          { "Fast select", "q931.fast_select",
            FT_UINT8, BASE_HEX, VALS(q931_fast_selected_vals), 0x18,
            NULL, HFILL }
        },
        { &hf_q931_pl_window_size_forward_value,
          { "Forward value", "q931.pl_window_size.forward_value",
            FT_UINT8, BASE_DEC, NULL, 0x7F,
            NULL, HFILL }
        },
        { &hf_q931_pl_window_size_backward_value,
          { "Backward value", "q931.pl_window_size.backward_value",
            FT_UINT8, BASE_DEC, NULL, 0x7F,
            NULL, HFILL }
        },
        { &hf_q931_packet_size_forward_value,
          { "Forward value", "q931.packet_size.forward_value",
            FT_UINT8, BASE_DEC, NULL, 0x7F,
            NULL, HFILL }
        },
        { &hf_q931_packet_size_backward_value,
          { "Backward value", "q931.packet_size.backward_value",
            FT_UINT8, BASE_DEC, NULL, 0x7F,
            NULL, HFILL }
        },
        { &hf_q931_cug_indication,
          { "CUG indication", "q931.cug_indication",
            FT_UINT8, BASE_HEX, VALS(q931_cug_indication_vals), 0x07,
            NULL, HFILL }
        },
        { &hf_q931_cug_index_code,
          { "CUG index code", "q931.cug_index_code",
            FT_STRING, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_reverse_charging_ind,
          { "Reverse charging indication", "q931.reverse_charging_ind",
            FT_UINT8, BASE_HEX, VALS(q931_reverse_charging_indication_vals), 0x07,
            NULL, HFILL }
        },
        { &hf_q931_extension_reason,
          { "Reason for redirection", "q931.extension.reason",
            FT_UINT8, BASE_HEX, VALS(q931_redirection_reason_vals), 0x0F,
            NULL, HFILL }
        },
        { &hf_q931_party_subaddr_type,
          { "Type of subaddress", "q931.party_subaddr.type",
            FT_UINT8, BASE_HEX, VALS(q931_subaddress_type_vals), 0x70,
            NULL, HFILL }
        },
        { &hf_q931_party_subaddr_odd_even_indicator,
          { "Odd/even indicator", "q931.party_subaddr.odd_even",
            FT_UINT8, BASE_HEX, VALS(q931_odd_even_indicator_vals), 0x08,
            NULL, HFILL }
        },
        { &hf_q931_party_subaddr,
          { "Subaddress", "q931.party_subaddr",
            FT_BYTES, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_restart_indicator,
          { "Restart indicator", "q931.restart_indicator",
            FT_UINT8, BASE_HEX, VALS(q931_restart_indicator_class_vals), 0x07,
            NULL, HFILL }
        },
        { &hf_q931_high_layer_compat_data,
          { "Data", "q931.high_layer_compat.data",
            FT_BYTES, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_user_protocol_discriminator,
          { "Protocol discriminator", "q931.user.protocol_discriminator",
            FT_UINT8, BASE_HEX|BASE_EXT_STRING, &q931_protocol_discriminator_vals_ext, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_user_information_len,
          { "User information", "q931.user.len",
            FT_UINT32, BASE_DEC, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_user_information_str,
          { "User information", "q931.user.string",
            FT_STRING, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_user_information_bytes,
          { "User information", "q931.user.bytes",
            FT_BYTES, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_party_category,
          { "Party category", "q931.party_category",
            FT_UINT8, BASE_HEX, VALS(q931_party_category_vals), 0x07,
            NULL, HFILL }
        },
        { &hf_q931_congestion_level,
          { "Congestion level", "q931.congestion_level",
            FT_UINT8, BASE_HEX, VALS(q931_congestion_level_vals), Q931_IE_SO_IE_MASK,
            NULL, HFILL }
        },
        { &hf_q931_repeat_indicator,
          { "Repeat indicator", "q931.repeat_indicator",
            FT_UINT8, BASE_HEX, VALS(q931_repeat_indication_vals), Q931_IE_SO_IE_MASK,
            NULL, HFILL }
        },
        { &hf_q931_out_band_negotiation,
          { "Out-band negotiation", "q931.out_band_negotiation",
            FT_BOOLEAN, 8, TFS(&tfs_possible_not_possible), 0x40,
            NULL, HFILL }
        },
        { &hf_q931_layer_1,
          { "Layer 1", "q931.layer_1",
            FT_BOOLEAN, 8, TFS(&tfs_asynchronous_synchronous), 0x40,
            NULL, HFILL }
        },
        { &hf_q931_layer_1_in_band_negotiation,
          { "Layer 1 in-band negotiation", "q931.layer_1_in_band_negotiation",
            FT_BOOLEAN, 8, TFS(&tfs_possible_not_possible), 0x20,
            NULL, HFILL }
        },
        { &hf_q931_send_data_net_independent_clock,
          { "Send data with network independent clock", "q931.send_data_net_independent_clock",
            FT_BOOLEAN, 8, TFS(&tfs_required_not_required), 0x10,
            NULL, HFILL }
        },
        { &hf_q931_accept_data_net_independent_clock,
          { "Accept data with network independent clock", "q931.accept_data_net_independent_clock",
            FT_BOOLEAN, 8, TFS(&tfs_accepted_not_accepted), 0x08,
            NULL, HFILL }
        },
        { &hf_q931_send_data_flow_control,
          { "Send data with flow control mechanism", "q931.send_data_flow_control",
            FT_BOOLEAN, 8, TFS(&tfs_required_not_required), 0x04,
            NULL, HFILL }
        },
        { &hf_q931_accept_data_flow_control,
          { "Accept data with flow control mechanism", "q931.accept_data_flow_control",
            FT_BOOLEAN, 8, TFS(&tfs_accepted_not_accepted), 0x2,
            NULL, HFILL }
        },
        { &hf_q931_rate_adaption_header,
          { "Rate adaption header", "q931.rate_adaption_header",
            FT_BOOLEAN, 8, TFS(&tfs_present_not_present), 0x40,
            NULL, HFILL }
        },
        { &hf_q931_multiple_frame_establishment,
          { "Multiple frame establishment", "q931.multiple_frame_establishment",
            FT_BOOLEAN, 8, TFS(&tfs_supported_not_supported), 0x20,
            NULL, HFILL }
        },
        { &hf_q931_mode_of_operation,
          { "mode of operation", "q931.mode_of_operation",
            FT_BOOLEAN, 8, TFS(&tfs_protocol_sensative_bit_transparent), 0x10,
            NULL, HFILL }
        },
        { &hf_q931_message_originator,
          { "Message originator", "q931.message_originator",
            FT_BOOLEAN, 8, TFS(&tfs_assignor_default), 0x04,
            NULL, HFILL }
        },
        { &hf_q931_negotiation_is_done,
          { "Negotiation is done", "q931.negotiation_is_done",
            FT_BOOLEAN, 8, TFS(&tfs_in_out_band), 0x02,
            NULL, HFILL }
        },
        { &hf_q931_bearer_capability_duplex,
          { "Duplex", "q931.bearer_capability.duplex",
            FT_BOOLEAN, 8, TFS(&tfs_full_half), 0x40,
            NULL, HFILL }
        },
        { &hf_q931_network_service,
          { "Network service", "q931.network_service",
            FT_BOOLEAN, 8, TFS(&tfs_user_provider), 0x80,
            NULL, HFILL }
        },
        { &hf_q931_extension_condition_type,
          { "Type", "q931.extension_condition_type",
            FT_BOOLEAN, 8, TFS(&tfs_abnormal_normal), 0x40,
            NULL, HFILL }
        },
        { &hf_q931_extension_condition,
          { "Condition", "q931.extension_condition",
            FT_UINT8, BASE_HEX, VALS(q931_cause_condition_vals), 0x03,
            NULL, HFILL }
        },
        { &hf_q931_pl_request,
          { "Request", "q931.pl_request",
            FT_BOOLEAN, 8, TFS(&tfs_pl_request), 0x04,
            NULL, HFILL }
        },
        { &hf_q931_pl_binary_confirmation,
          { "Confirmation", "q931.pl_binary_confirmation",
            FT_BOOLEAN, 8, TFS(&tfs_link_end), 0x02,
            NULL, HFILL }
        },
        { &hf_q931_pl_modulus,
          { "Modulus", "q931.pl_modulus",
            FT_BOOLEAN, 8, TFS(&tfs_pl_modulus), 0x01,
            NULL, HFILL }
        },
        { &hf_q931_data,
          { "Data", "q931.data",
            FT_BYTES, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_information_element,
          { "Information element", "q931.information_element",
            FT_UINT8, BASE_DEC, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_information_element_len,
          { "Length", "q931.information_element_len",
            FT_UINT8, BASE_DEC, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_date_time,
          { "Date/time", "q931.date_time",
            FT_BYTES, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_more_data,
          { "More data", "q931.more_data",
            FT_NONE, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_sending_complete,
          { "Sending complete", "q931.sending_complete",
            FT_NONE, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_message_segment,
          { "Message segment", "q931.message_segment",
            FT_BYTES, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_missing_info_element,
          { "Missing information element", "q931.missing_info_element",
            FT_UINT8, BASE_HEX, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_insufficient_info_element,
          { "Insufficient information element", "q931.insufficient_info_element",
            FT_UINT8, BASE_HEX, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_cumulative_transit_delay,
          { "Cumulative transit delay", "q931.cumulative_transit_delay",
            FT_UINT16, BASE_DEC, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_requested_end_to_end_transit_delay,
          { "Requested end-to-end transit delay", "q931.requested_end_to_end_transit_delay",
            FT_UINT16, BASE_DEC, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_maximum_end_to_end_transit_delay,
          { "Maximum end-to-end transit delay", "q931.maximum_end_to_end_transit_delay",
            FT_UINT16, BASE_DEC, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_transit_delay,
          { "Transit delay", "q931.transit_delay",
            FT_UINT16, BASE_DEC, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_display_information,
          { "Display information", "q931.display_information",
            FT_STRING, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_keypad_facility,
          { "Keypad facility", "q931.keypad_facility",
            FT_STRING, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_avaya_display,
          { "Avaya Display", "q931.avaya_display",
            FT_STRING, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_locking_codeset,
          { "Locking codeset", "q931.locking_codeset",
            FT_UINT8, BASE_DEC, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_q931_protocol_negotiation,
          { "Protocol negotiation", "q931.protocol_negotiation",
            FT_BOOLEAN, 8, TFS(&tfs_protocol_negotiation), 0x08,
            NULL, HFILL }
        },
    };

#define NUM_INDIVIDUAL_ELEMS    3
    static gint *ett[NUM_INDIVIDUAL_ELEMS + NUM_IE];

    static ei_register_info ei[] = {
        { &ei_q931_invalid_length, { "q931.invalid_length", PI_MALFORMED, PI_ERROR, "Invalid length", EXPFILL }},
        { &ei_q931_date_time, { "q931.date_time.invalid", PI_MALFORMED, PI_ERROR, "Date/time: Invalid length", EXPFILL }},
        { &ei_q931_information_element, { "q931.information_element.unknown", PI_PROTOCOL, PI_WARN, "Unknown information element", EXPFILL }},
        { &ei_q931_incomplete_ie, { "q931.incomplete_ie", PI_MALFORMED, PI_ERROR, "Incomplete IE in the 1st segment", EXPFILL }},
    };

    module_t *q931_module;
    expert_module_t* expert_q931;

    ett[0] = &ett_q931;
    ett[1] = &ett_q931_segments;
    ett[2] = &ett_q931_segment;

    last_offset = NUM_INDIVIDUAL_ELEMS;

    for (i=0; i < NUM_IE; i++, last_offset++)
    {
        ett_q931_ie[i] = -1;
        ett[last_offset] = &ett_q931_ie[i];
    }

    proto_q931 = proto_register_protocol("Q.931", "Q.931", "q931");
    proto_register_field_array (proto_q931, hf, array_length(hf));
    proto_register_subtree_array(ett, array_length(ett));
    expert_q931 = expert_register_protocol(proto_q931);
    expert_register_field_array(expert_q931, ei, array_length(ei));
    register_init_routine(q931_init);
    register_cleanup_routine(q931_cleanup);

    q931_handle = register_dissector("q931", dissect_q931, proto_q931);
    q931_tpkt_handle = register_dissector("q931.tpkt", dissect_q931_tpkt, proto_q931);
    q931_tpkt_pdu_handle = create_dissector_handle(dissect_q931_tpkt_pdu,
        proto_q931);
    q931_over_ip_handle = register_dissector("q931.over_ip", dissect_q931_over_ip, proto_q931);
    register_dissector("q931.ie", dissect_q931_ie_cs0, proto_q931);
    register_dissector("q931.ie.cs7", dissect_q931_ie_cs7, proto_q931);

    /* subdissector code */
    codeset_dissector_table = register_dissector_table("q931.codeset", "Q.931 Codeset", FT_UINT8, BASE_HEX, DISSECTOR_TABLE_ALLOW_DUPLICATE);
    ie_dissector_table = register_dissector_table("q931.ie", "Q.931 IE", FT_UINT16, BASE_HEX, DISSECTOR_TABLE_ALLOW_DUPLICATE);
    q931_user_heur_subdissector_list = register_heur_dissector_list("q931_user");

    q931_module = prefs_register_protocol(proto_q931, NULL);
    prefs_register_bool_preference(q931_module, "desegment_h323_messages",
        "Reassemble Q.931 messages spanning multiple TCP segments",
        "Whether the Q.931 dissector should reassemble messages spanning multiple TCP segments."
        " To use this option, you must also enable \"Allow subdissectors to reassemble TCP streams\" in the TCP protocol settings.",
        &q931_desegment);
    prefs_register_bool_preference(q931_module, "reassembly",
        "Reassemble segmented Q.931 messages",
        "Reassemble segmented Q.931 messages (Q.931 - Annex H)",
        &q931_reassembly);
    prefs_register_bool_preference(q931_module, "iso_iec_cause_coding",
        "Decode ISO/IEC cause coding standard as ITU-T",
        "Decode ISO/IEC cause coding standard as ITU-T",
        &g931_iso_iec_cause);
    /* Register for tapping */
    q931_tap = register_tap("q931");
}

void
proto_reg_handoff_q931(void)
{
    dissector_add_uint("lapd.sapi", LAPD_SAPI_Q931, q931_handle);
    dissector_add_uint("sctp.ppi", H323_PAYLOAD_PROTOCOL_ID, q931_over_ip_handle);

    /*
     * Attempt to get a handle for the H.225 dissector.
     * If we can't, the handle we get is null, and we'll just
     * dissect putatively-H.255 Call Signaling stuff as User
     * Information.
     */
    h225_handle = find_dissector("h225");

    data_handle = find_dissector("data");

    /*
     * For H.323.
     */
    heur_dissector_add("tcp", dissect_q931_tpkt_heur, "Q.931 over TPKT over TCP", "q931_tcp", proto_q931, HEURISTIC_ENABLE);
}

static void reset_q931_packet_info(q931_packet_info *pi)
{
    if(pi == NULL) {
        return;
    }

    pi->calling_number = NULL;
    pi->called_number = NULL;
    pi->cause_value = 0xFF;
    pi->crv = -1;
}

/*
 * Editor modelines  -  http://www.wireshark.org/tools/modelines.html
 *
 * Local variables:
 * c-basic-offset: 4
 * tab-width: 8
 * indent-tabs-mode: nil
 * End:
 *
 * vi: set shiftwidth=4 tabstop=8 expandtab:
 * :indentSize=4:tabSize=8:noTabs=true:
 */