[Iaxclient-devel] Serious Audio/Timing Issues with Iax Clients

[Steven S. <ss...@so...>]

Ok, I know a number of people out there have experienced audio and/or 
timing issues recently that have made for really bad audio quality (from 
barely listenable to completely unlistenable) using soft phones written 
with iaxClient.

1)  The most common symptom seems to be serious jitter or cut-out on 
audio on some SIP devices.  A user described it as listening to somebody 
shouting at you through a fan.

2)  This only affects the audio output on the SIP device side of the 
call (i.e. audio from the SIP device to the IAX Phone sounds fine). 

3)  There does not seem to be any issue with signaling (i.e. the calls 
don't get torn down prematurely).

4)  The problem seems to be worse on some SIP phones than on others.  My 
ACT phone and my ariaVoice phone both seem relatively unaffected, while 
my Cisco 7960 is ALWAYS TERRIBLE.

5)  This problem seems to be fairly recent.  At least I only started 
noticing it in recent months.  In my case, two things have changed: 1) I 
installed and began using the Cisco 7960, and 2) I upgraded my Asterisk 
to 1.0.2.

6)  The problem does not seem to be codec dependent.  The issue occurs 
on regardless of the codec used.  I have experienced the problem with 
GSM, iLBC, Speex, uLaw and aLaw.  It's not the codecs.

7)  The problem seems to happen even with rather old versions of IAX 
Phone (and other iaxClient-based programs).  I have used versions of IAX 
Phone and iaxComm that are 6 months old and they exhibit this problem as 
well.

8)  The problem does not seem to be limited to iaxClient-based systems.  
I tried a recent build of FireFly and the same thing happens.  Adam uses 
the libiax2 code (with a few minor modifications) but not the iaxClient 
wrapper.

All of these things seem to me to point to a change in the chan_iax2 
code in Asterisk.  A quick review of the Asterisk CVS log for shows a 
fair number of changes over the past few months.  I wonder if anybody 
out there who has run into this issue might have time to install an 
older release of Asterisk -- something from June or July, perhaps, and 
see if the issue disappears.

Any thoughts would be appreciated.

Thanks,

Steve