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7.5 KiB

(CAPI*) chan_capi a Common ISDN API 2.0 implementation for Asterisk
Copyright (C) 2005 Cytronics & Melware
Armin Schindler <>
Reworked, but based on the work of
Copyright (C) 2002-2005 Junghanns.NET GmbH
Klaus-Peter Junghanns <>
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 and bugfixers (listed in chronological order) :)
Lele Forzani <>
Florian Overkamp <>
Gareth Watts <>
Jeff Noxon <>
Petr Michalek <>
Jan Stocker
Frank Sautter, levigo group
(...and all the others that i forgot..) :-)
This chan_capi version includes:
- Multiple controller support
- CID,DNID (callling party, called party)
- 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_pvt.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
- CapiECT will announce the callerID since it gets lost on most isdn pbxes
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)
- Added app_capiNoES for disabling the primitive echo suppressor, use this
before you start recording voicemail or your files may get choppy
- Added app_capiFax to receive faxes over CAPI (see below)
- Fixes for BSD (Jan Stocker)
- Support 'type of number'.
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
With this application, special capi commands and features can be used.
Call Deflection:
Forwards an unanswered call to another number.
exten => s,1,capicommand(deflect|12345678)
Helper applications
Puts an answered call on hold, this has nothing to do with asterisk's onhold
thingie (music et al)
After putting a call onhold, never use the Wait application!
Gets the holded call back
Explicit call transfer of the call on hold (must put call on hold first!)
exten => s,1,Answer
exten => s,2,capiHOLD
exten => s,3,capiECT,55:50
Will ECT the call to 50 using 55 as the callerid/outgoing MSN
Using CLIR
Use the SetCallerPres() application before you dial:
exten => _X.,1,SetCallerPres(prohib_not_screened)
exten => _X.,2,Dial(CAPI/contr1/${EXTEN})
Enjoying early B3 connects (inband call progress, tones and announcements)
Early B3 is configurable in the dialstring parameters.
If you set a 'b', early B3 will always be used, also if the call fails,
because the number is unprovisioned, etc ...
If you set a 'B', early B3 will only be used on successful calls,
giving you ring indication,etc...
Don't use indications in the Dial command, your local exchange will do that for
exten => _X.,1,Dial(CAPI/contr1/${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/${EXTEN}/b,30,r)
(always early B3, fake indicatons if the exchange does not give us
exten => _X.,1,Dial(CAPI/contr1/${EXTEN}/B,30,r)
(early B3 on success, fake indicatons if the exchange does not give us
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:
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:
exten => 12345678,1,Dial(SIP/phone1)
exten => 12345678,2,Hangup
Short HOWTO of 'capiAnswerFax':
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 capiAnswerFax() instead of
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 capiAnswerFax().
Example of use :
line number 123, play something, if a fax tone is detected, handle it
line number 124, answer directly in fax mode
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)
exten => s,1,capiAnswerFax(/tmp/${UNIQUEID})
exten => s,2,Hangup()
exten => h,1,deadagi,fax.php // Run sfftobmp and mail it.
The output of capiAnswerFax 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)