[Asterisk-Users] I have put iLBC at the top

[Vic Cross]

On Fri, 21 May 2004, nicolas wrote:

> I want use iLBC and have following in mind, please help me is it possible ?
> 
> ISDN <-----(ALAW)-----> * <-----(ALAW)-----> SNOM
> SIP  <-----(iLBC)-----> * <-----(ALAW)-----> SNOM
> 
> 1. ISDN incoming codec is ALAW SNOM codec should be ALAW (can't be iLBC
> because a lack of codec).
> 2. SIP incoming codec should be iLBC (snom is ALAW).
> 3. SIP outgoing codec should be iLBC /snom is ALAW).
> 
> I thought * is converting beetwen iLBC and ALAW but * force the use of ALAW
> always, because i can not disable ALAW (need is for ISDN).

I think you may have taken me too literally when I said before that your
ISDN uses ALAW.  It is true that EuroISDN uses G.711 ALAW as the codec for
transmission of your digitised voice over a B-channel.  Your configuration
does not need to take this into account, though.

The fact that ISDN is ALAW internally should be irrelevant to how you
configure the rest of your links.  The only reason I mentioned it was that
it might have helped explain why ALAW was used in preference to your other
codecs on your VoIP connections.  It seemed reasonable to me that 
*internally* Asterisk would recognise that the data coming in from the 
ISDN was already in ALAW, and give preference to that codec for other call 
legs -- in fact, I have no idea whether Asterisk makes such decisions.

If you want to use iLBC for SIP, do it -- you can remove ALAW from those
configs if you wish.  This will force Asterisk to transcode ALAW to iLBC.  

Sorry if I caused confusion.


Cheers,
Vic Cross