(CAPI*) chan_capi a Common ISDN API 2.0 implementation for Asterisk

 Copyright (C) 2005 Cytronics & Melware
 Armin Schindler <armin@melware.de>
 
 Reworked, but based on the work of
 Copyright (C) 2002-2005 Junghanns.NET GmbH
 Klaus-Peter Junghanns <kpj@junghanns.net>

This program is free software and may be modified and distributed under
the terms of the GNU Public License. There is _NO_ warranty for this!

Thanks go to the debuggers, bugfixers and contributors :)
===========================================================================
Lele Forzani <lele@windmill.it>
Florian Overkamp <florian@obsimref.com>
Gareth Watts <gareth@omnipotent.net>
Jeff Noxon <jeff@planetfall.com>
Petr Michalek <petr.michalek@aca.cz>
Jan Stocker
Frank Sautter, levigo group
Hans Petter Selasky

(...and all the others that have been forgotten...) :-)

This chan_capi version includes:
================================
- Multiple controller support
- CID,DNID (callling party, called party)
- CLIR/CLIP
- Supplementary services, CD,HOLD,RETRIEVE,ECT
- DTMF (dependend on card) + software DTMF support
- Early B3 connects (always,success,never)
- Digital audio (what did you think?)
- Incoming/outgoing calls
- Overlap sending (dialtone and additional digits)
- E(xplicit) C(all) T(ransfer) (...although it's done implicit-but don't tell!)
- Tuneable latency:  you can configure the size of B3 blocks at compile time
  (in chan_capi.h, AST_CAPI_MAX_B3_BLOCK_SIZE)
  The default is 160 samples, for non-VoIP use you can tune it down to 130
- Use asterisks internal DSP functions for DTMF
- Alaw support 
- Ulaw support! 
- Eicon CAPI echo cancelation (echocancel=1)
- Reject call waiting (ACO)
- DID for Point to Point mode (a.k.a overlap receiving)
- Rx/Tx gains (rxgain=1.0)
- Call deflection on circuit busy (deflect=12345678)
- (Inter)national dialing prefix (for callerid) configurable in capi.conf
- CLI command "capi info" shows B channel status of chan_capi
  The called party can press # to drop the call
- Catch all MSN (incomingmsn=*)
- Some configuration enhancements (msn=123,124,125 and controller=1,2,3,4)
- Added accountcode= 
- Echo squelching (echosquelch=1)
- Callgroup support
- report correct DIALSTATUS and HANGUPCAUSE.
- Updated to support the new frame->delivery field
- Compiles with different Asterisk versions (automatic build configuration)
- receive faxes over CAPI (see below)
- Fixes and compatibility for BSD (Jan Stocker and Hans Petter Selasky)
- Support 'type of number'.
- ISDN hold.
- CAPI Line Interconnect.

The Dial string
===============

  Example:        Dial(CAPI/g<group>/<destination>[/<params>])
  Or:             Dial(CAPI/contr<controller>/<destination>[/<params>])
  Or:             Dial(CAPI/<interface-name>/<destination>[/<params>])

  'group' can be a value, comma separated list of values or a range
  using '-'. The according interface is found by searching a match with
  the 'group' specified in the capi.conf for each interface.

  'params' is an optional part to set special settings for this call.
  The string consists of a list of characters with the following meaning:
   'b' : early B3 always.
   'B' : early B3 on successful calls only.
   'o' : use overlap sending of number if number is longer than 2 digits
         (This is useful, when further digits shall be send to complete the
	 destination address).

  If the <interface-name> is used in dialstring, be sure the name (specified
  in capi.conf) does not start with 'contr' or 'g'.

  CLIP/CLIR uses the calling presentation of the calling channel, which can
  be modified using the SetCallerPres() application. Use
  SetCallerPres(prohib_not_screened) for CLIR. That is why the msn= param in
  capi.conf has been removed. The callerID is also taken from the calling channel.


CAPI command application
========================
chan_capi provides an additional Asterisk application
   capicommand()
With this application, special capi commands and features can be used.

Call Deflection:
    Forwards an unanswered call to another number.
        Example:
        exten => s,1,capicommand(deflect|12345678)
  
Fax receive:
    Receive a fax using CAPI.
        Example:
        exten => s,1,capicommand(receivefax|/tmp/${UNIQUEID}|+49 6137 555123|Asterisk)
	(more see below)

Enable/Disable echosquelch:
    Enable or disable a very primitive echo suppressor.
    Disable this before you start recording voicemail or your files may get choppy.
        Example:
        exten => s,1,capicommand(echosquelch|yes)
          or
        exten => s,1,capicommand(echosquelch|no)

Malicious Call Identification:
    Report a call of malicious nature.
        Example:
        exten => s,1,capicommand(malicious)

Hold:
    Puts an answered call on hold, this has nothing to do with asterisk's onhold
    thingie (music et al).
    An optional parameter is the name of the variable which shall be set with
    the reference ID of the call on hold.
        Example:
        exten => s,1,capicommand(hold)
         or
        exten => s,1,capicommand(hold|MYHOLDVAR)

Holdtype:
    Set the type of 'hold'. When Asterisk wants to put the call on hold, the specified method
    will be used.
        Example:
        exten => s,1,capicommand(holdtype|local)  ;no hold, Asterisk can play MOH
         or
        exten => s,1,capicommand(holdtype|hold)   ;ISDN-HOLD 
         or
        ; not yet implemented
        exten => s,1,capicommand(holdtype|notify) ;notify the peer only, Asterisk can play MOH

       
Retrieve:
    Gets back the holded call. An optional parameter is the reference ID of the call
    on hold.
        Example:
        exten => s,1,capicommand(retrieve)
         or
        exten => s,1,capicommand(retrieve|${MYHOLDVAR})

ECT:
    Explicit call transfer of the call on hold (must put call on hold first!)
        Example:
        exten => s,1,capicommand(ect|${MYHOLDVAR})
         or
        [macro-capiect]
        exten => s,1,capicommand(ect)
        [default]
        exten => s,1,capicommand(hold)
        exten => s,2,Wait(1)
        exten => s,3,Dial(CAPI/contr1/1234,60,M(capiect))


Using CLIR
==========
Use the SetCallerPres() application before you dial:
	exten => _X.,1,SetCallerPres(prohib_not_screened)
	exten => _X.,2,Dial(CAPI/contr1/${EXTEN})


Enjoying early B3 connects (inband call progress, tones and announcements)
==========================================================================
Early B3 is configurable in the dialstring parameters.
If you set a 'b', early B3 will always be used, also if the call fails,
because the number is unprovisioned, etc ...
If you set a 'B', early B3 will only be used on successful calls, 
giving you ring indication,etc...

Don't use indications in the Dial command, your local exchange will do that for 
you:
	exten => _X.,1,Dial(CAPI/contr1/${EXTEN}/B,30)		
		(early B3 on success)
	
	exten => _X.,1,Dial(CAPI/contr1/${EXTEN}/b,30)	
		(always early B3)
	
	exten => _X.,1,Dial(CAPI/contr1/${EXTEN},30,r)		
		(no early B3, fake ring indication)

	exten => _X.,1,Dial(CAPI/contr1/${EXTEN}/b,30,r)		
		(always early B3, fake indicatons if the exchange does not give us 
		indications)
	
	exten => _X.,1,Dial(CAPI/contr1/${EXTEN}/B,30,r)		
		(early B3 on success, fake indicatons if the exchange does not give us 
		indications)
    
For normal PBX usage you would use the "b" option, always early B3.

Overlap sending (a.k.a. real dialtone)
======================================
When you dial an empty number, and have early B3 enabled, with:
    Dial(CAPI/g1//b)
The channel will come up at once and give you the dialtone it gets from the 
local exchange.
At this point the channel is like a legacy phone, now you can send DTMF digits 
to dial.    

Example context for incoming calls on MSN 12345678:
===================================================

[capi-in]
exten => 12345678,1,Dial(SIP/phone1)
exten => 12345678,2,Hangup


Short HOWTO of capicommand(receivefax|<filename>[|<stationid>|<headline>]):
==========================================================================
For those of you who have a CAPI card with an on-board DSP (like some Eicon and
DIVA Server), this patch allows you to receive faxes.
If you want to answer a channel in fax mode, use capicommand(receivefax|...)
instead of Answer()
If you use Answer(), you will be in voice mode. If the hardware DSP detects 
fax tone, you can switch from voice to fax mode by calling capicommand(receivefax|...).
The parameter <filename> is mandatory and the parameters <stationid> and
<headline> are optional.

Example of use :
line number 123, play something, if a fax tone is detected, handle it
line number 124, answer directly in fax mode

[incoming]
exten => 123,1,Answer()
exten => 123,2,BackGround(jpop)
exten => 124,1,Goto(handle_fax,s,1)
exten => fax,1,Goto(handle_fax,s,1)

[handle_fax]
exten => s,1,capicommand(receivefax|/tmp/${UNIQUEID}[|<stationid>|<headline>])
exten => s,2,Hangup()
exten => h,1,deadagi,fax.php // Run sfftobmp and mail it.

The output of capicommand(receivefax|...) is a SFF file.
Use sfftobmp to convert it.
With a DIVA Server, following features are provided:
 - fax up to 33600
 - high resolution
 - Color Fax 
 - JPEG Compression is disabled (not tested yet)


Asterisk variables used/set by chan_capi
========================================

CALLEDTON
    The 'type of number' value of the called number is saved in this variable on
    incomming call.

_CALLERHOLDID
    If a call is put on hold (ISDN-HOLD), the reference id is saved in this variable.
    This variable is inherited as CALLERHOLDID to the dialed channel and will be used
    if e.g. capicommand(ect) is used to transfer the held call.

CONNECTEDNUMBER
    Can be set before answering and if set, the content is used for
    IE 'Connected Number' on answering.

FAXEXTEN
    If chan_capi sends the call to extensions 'fax', the original extension number
    is saved in this variable.

PRI_CAUSE
    If set, this value will be used as hangup cause on hangup.

REDIRECTINGNUMBER
    On incoming call, if the call was redirected to you by someone, the
    number of the redirecting party is saved in this variable.

REDIRECTREASON
    If the incoming call was redirected to you, this variable is set
    with the reason value.

CALLINGSUBADDRESS
    If set on dial(), the calling subaddress will be set to the content.

CALLEDSUBADDRESS
    If set on dial(), the called subaddress will be set to the content.
  

Functions (available with newer Asterisk only)
==============================================

VANITYNUMBER(<vanitynumber>)
    Converts the 'vanitynumber' into a digit-only string. International keypad is
    used, e.g. ABC=1, DEF=2, ...