[asterisk-users] Forcing a CODEC

[Jaap Winius]

Hi folks,

How can I take advantage of a high-bandwidth CODEC, like G.722, for  
internal communications at my site, but use G.711 (alaw/ulaw) for all  
other outgoing calls? I need G.711 to support Inband DTMF signaling.

As my site has multiple locations that are tied together with IAX  
trunks, I was hoping that it would be possible to specify alaw and  
ulaw as the first two CODEC choices for the SIP phones, as well as in  
their sip.conf configurations, but that I could use the IAX trunks  
(with bandwidth=high) to force the phones to use their third CODEC  
choice, g722, because that would be the only CODEC specified for the  
IAX trunks (following disallow=all).

Unfortunately, that doesn't work. Although the Asterisk console  
reports that g722 is being used, when I listen to the connection it's  
obvious that a G.711 CODEC is being used. Curiously, the reverse does  
work: if g722 is specified as the first CODEC of choice for the  
phones, it is possible to use the IAX trunks to force them to use  
alaw/ulaw instead.

Is a solution to this problem?

I'm using Debian squeeze with Asterisk 1.6.2.9.

Cheers,

Jaap