[Asterisk-Users] Problem with IAX2 jitterbuffer and DTMF reception with 1.2.0

[Steve Kann]

Rich Adamson wrote:

>>I've noticed that if I enable the jitterbuffer in iax.conf with Asterisk 
>>1.2.0 that Asterisk stops responding to incoming DTMF frames for calls 
>>between Teliax and my server.  I've used "iax2 debug" and Ethereal to 
>>confirm that Teliax is, in fact, sending the frames.
>>
>>I only have two IAX2 connections (one a softphone on my local network 
>>and the Teliax registration).  The softphone does not experience the 
>>problem (DTMF frames sent from the softphone to * are recognized with 
>>the jitter buffer enabled).
>>
>>Everything else about the connection with Teliax is fine when the jitter 
>>buffer is enabled.
>>
>>"iax2 show channels" reports a 40 ms delay with the Teliax connection.
>>
>>Any ideas?
>>
>>My iax.conf is:
>>
>>[general]
>>bandwidth=low
>>jitterbuffer=no  ; setting this to yes causes DTMF frames from Teliax to 
>>be ignored (for my server anyway), apparently
>>forcejitterbuffer=no
>>
>>
>>register => 
>>XXXXXXXXXXXXXXXXXX:XXXXXXXXXXX at voip-co3.teliax.com                 
>>
>>tos=lowdelay
>>autokill=yes
>>
>>
>>
>>[bboatrig]
>>type=friend
>>host=dynamic
>>context=default
>>auth=md5,rsa,plaintext
>>secret=XXXXXXXXXX
>>callerid="Laptop" <7020>
>>accountcode=bboatrig0
>>
>>[teliax]
>>context=incoming-voip-trusted
>>type=friend
>>host=voip-co3.teliax.com
>>auth=md5
>>secret=XXXXXXXXXXXXXXXXXXXXX
>>disallow=all
>>allow=ulaw
>>allow=alaw
>>allow=gsm
>>    
>>
>
>Had the same issue with them for some time using cvs-head. I simply
>left the jitterbuffer turned off and really haven't had an issue.
>  
>
If you guys ran ethereal on the packets coming from teliax, did you find 
that the DTMF frames had timestamps that were around the same as the 
surrounding voice frames? 

If asterisk isn't seeing the DTMF frames at all, it could just be that 
teliax is sending them with timestamps far into the future or something, 
so the jitterbuffer is just putting them back in order.  For example, if 
teliax sends frames that look like this

Voice: 0ms
Voice: 20ms
Voice: 40ms
[...]
Voice: 1000ms
Voice: 1020ms
DTMF: 22333444ms
Voice: 1040ms

Then, the jitterbuffer will end up holding onto the DTMF frame, for.. a 
while..

-SteveK

>I opened a trouble ticket with them and they quickly blamed asterisk
>for not fixing a problem. Best guess is they are running an older
>version of iax2 (probably modified) and haven't taken the time to
>upgrade.
>
>There is also a known issue with using trunk=yes and ilbc. Bug has been
>opened on that one.
>
>
>
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