[asterisk-users] speex, ilbc and g729 codecs, GSM with IAX

[bilal ghayyad]

Dears;

I do not know if any had experience in using speex or
ilbc with IAX and got good results, because I am
facing a problem with GSM.

I am facing a noise problem when I am using GSM with
IAX trunk as following:

IP Phone (G711) ---> Local Asterisk Box ---> IAX Trunk
using GSM codec ---> Remote Asterisk Box ---> Digium
Card (FXO) to terminate the call to the destination

While no noise happen if that senario is happening:

IP Phone (G711) ---> Local Asterisk Box ---> IAX Trunk
using GSM codec ---> Remote Asterisk Box ---> Digium
Card (FXS) to an extension

I tried to use GSM with IAX trunk, and actually I got
a problem that: when I am using IP Phone (Polycom 320,
with G711 codec) and placed a call, that call will go
via the IAX trunk to the remote Asterisk Box, then
using the Digium TDM22B card to terminate the call via
the PSTN analoge lines, there is a noise coming with
the voice! This noise does not appear if we do not use
the "IAX trunk and if the call is not going to be
terminated via the Digium Card (FXO) on the remote
Asterisk Box (if we use IAX trunk and we call an
extension (FXS) on a remote Asterisk but not the PSTN
and the FXO on the remote Asterisk, then no noise
appear).

So the noise happen only in that senario:

IP Phone (G711) ---> Local Asterisk Box ---> IAX Trunk
using GSM codec ---> Remote Asterisk Box ---> Digium
Card (FXO) to terminate the call to the destination

While no noise happen if that senario is happening:

IP Phone (G711) ---> Local Asterisk Box ---> IAX Trunk
using GSM codec ---> Remote Asterisk Box ---> Digium
Card (FXS) to an extension

I do not know if it is a matter of the GSM codec, or
if it is related to the digium card that it is the old
model.

But any one can advise if speex or ilbc will give
better performance than GSM with IAX trunk?

Any advise?
Regards
Bilal

--------------------
bilal ghayyad wrote:
> Hi List;
>
> Anyone tried to use speex, ilbc and g729 and come
back
> with a preferred one in the quality?
>
> Regards
> Bilal
>
>
>      

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Depends on what you're using it for.  We've had
excellent luck with
 iLBC 
for voice quality and g729 as well. Speex is better
than GSM, but not 
spectacularly.

The problem with all of them of course, is
transcoding. They have less 
of a bandwidth footprint for acceptable quality, but
more of a
 processor 
footprint.

N.