Summary:ASTERISK-16662: Asterisk messes up progress indication on q.931 ALERTING message
Reporter:Jiri Pokorny (jpokorny)Labels:
Date Opened:2010-09-09 05:10:54Date Closed:2011-06-07 14:00:56
Versions:Frequency of
Environment:Attachments:( 0) chan_dahdi.conf
( 1) ring
( 2) system.conf
Description:I am using asterisk with libpri 1.4.11, dahdi and two ISDN PRI E1 interfaces. Asterisk seems to have trouble with some outgoing calls signalization. Scenario:

1) inbound call to asterisk from user (SETUP and CALL PROCEEDING with user)
2) outbound call is dialed (SETUP and CALL PROCEEDING to PBX)
3) ALERTING message comes on the outbound channel, with no progress indication
4) ALERTING is sent to inbound channel, WITH progress indication 8 (Inband information or appropriate pattern now available)
5) but no sound is generated on the inbound channel
6) user hears nothing, few seconds later, he is connected

This scenario is catched up in the attached log. I recorded channels using dahdi_monitor to confirm the sound is not generated. Asterisk should either send ALERTING with no progress or generate the sound.

Unfortunately PBX does usually follow the ALERTING message with PROGRESS and inband audio, which works ok, so I can't reproduce it easily. I am not sure if this is chan_dahdi or libpri issue.
Comments:By: Leif Madsen (lmadsen) 2010-09-13 10:28:40

Per rmudgett:  "It is a chan_dahdi issue that is very very old (Since libpri support was added.).  It may involve the asterisk core since the ALERTING indicates that there is no audio.  Asterisk needs to either generate ringback tones or pass on that there is no audio available."

This is a note for future development.

By: Leif Madsen (lmadsen) 2010-09-13 10:29:47

rmudgett: AST_CONTROL_RINGING would need to be enhanced to pass if there is audio or not.

By: Richard Mudgett (rmudgett) 2010-09-20 14:59:47

It looks like this is really a configuration issue.  Chan_dahdi will always generate the ringback tone when it sends the ALERTING message thus it always indicates the progress indicator with inband information for audio calls.

Please attach your Asterisk chan_dahdi.conf and DAHDI system.conf files.

The tonezone related settings are needed.
* loadzone
* defaultzone

* tonezone

By: Jiri Pokorny (jpokorny) 2010-09-21 00:58:34

I have added complete config files as attachments. Short version:

loadzone = us
defaultzone = us

tonezone not set

By: Richard Mudgett (rmudgett) 2010-09-22 11:26:13

I think your call progress tones are either coming from your PBX or your PBX is occasionally not passing them through.  As I said earlier, chan_dahdi will always generate the ringback tone when it sends the ALERTING message and thus the sent ALERTING will always have the progress indicator for non-data calls.

As a test, you could change the DAHDI system.conf loadzone and defaultzone to uk instead of us and restart DAHDI.  You will hear a different ringback tone if the source of the tones is Asterisk.