How to Use a Trunk Codec (g726) that's Unsupported by an Endpoint? (transcoding)

Hi my Cisco 7960 equipment only supports g729/g711a/g711u, but we have found that the best balance of bandwidth usage and quality for our trunk to be g726 (by far).

Of course for internal communications between the endpoint and the PBX is fine on g711.

I have the trunk setup to accept g726 only (“disallow=all” and “allow=g726”). The problem is Asterisk balks when a 7960 tries to make a call since that endpoint only supports g711.

Calls from devices that support g726 work a-ok.

How do I get my PBX to transcode g711 to g726??


Note: I have tried putting in the extension settings for extension with the Cisco 7960 “disallow=all” and “allow=alaw&ulaw” to remind Asterisk that this extension does not support g726, and still no dice

Asterisk 1.8 / Free PBX 2.9

Also… if there’s no transcoding being accomplished, does that also mean asterisk isn’t doing the jitter buffer it is supposed to be doing?