[asterisk-users] odd sound between SIP & IAX clients

[Rich Adamson]

Pure guess without looking at the trace yet, its likely to be a timing 
issue (involving the codec translations) as opposed to the codec itself.

I've had good luck running g726 on iax links.


Joseph Love wrote:
> Well, you win, it's definitely codec related.
> 
> Switching to ulaw causes this issue to go away.
> I find it rather peculiar that the issue crops up in the first place.
> 
> If anyone is interested in packet traces of the problems I'm 
> encountering with GSM, I can manage to arrange for those.
> 
> Thanks,
> -Joe
> 
> On Jul 25, 2006, at 9:50 PM, Rich Adamson wrote:
> 
>> Joseph Love wrote:
>>> The issue which occurs is that the audio from the SIP client to the 
>>> IAX client will spend most of it's time sounded very robotic, and 
>>> garbled.  It is possible, although very difficult to understand 
>>> someone who is on the SIP phone.
>>> I have asterisk 1.2.10 configured with realtime with both IAX and SIP 
>>> clients.
>>> The SIP clients include a Grandstream gxp2000 hard phone, and 
>>> Counterpath's X-Lite 3 (for windows) softphone.
>>> The IAX clients tested include idefisk (both windows & mac), 
>>> JakenIAX, and LoudHush.
>>> GSM is the preferred codec of both IAX & SIP clients, and is indeed 
>>> the codec being used in all tests.
>>> Audio from the IAX to the SIP client does not experience any issues.  
>>> SIP to SIP (and presumably, although untested, IAX to IAX) 
>>> communication does not experience any issues.
>>> We also have a T1 card through which many calls have been placed, 
>>> both from the IAX and SIP phones, without any audio issues occurring, 
>>> in either case.
>>> If it weren't for that there have been multiple clients tested to 
>>> verify this robotic sound, I would cough it up to it being a 
>>> incompatability between the particular clients, but this occurs on 
>>> all SIP-IAX communication that has been tried.
>>> I'm running out of options as SIP-IAX intercommunication is kinda 
>>> expected (and necessary for me), and out of good softphones for the 
>>> mac, as most of the mac-compatible softphones are IAX2-based.
>>> Please let me know what additional information is needed to help me 
>>> debug this problem.
>>
>> Can you try different codecs just to rule out any issues with that? 
>> E.g., if both devices use ulaw, do you still have the same problem?
>>
>> I've used both iaxcomm and x-lite to communicate with cisco, polycom, 
>> grandsteam, etc, without that type of problem.
>>
>> Is it possible to obtain an ethereal trace of both the iax and sip/rtp 
>> streams in the same trace?  If so, a couple hundred packets should be 
>> more then enough to see what's going on.