CODEC Question

If anyone has the time and/or inclination to answer this one, I’d like to understand a little bit more about what’s happening on my Asterisk servers.

I’m seeing an interesting message in the log file when calls are placed on my outbound IAX2 trunk:

The call still goes through and decent quality audio is passed both ways. I’m just wondering what this means at a deeper level and what affect it’s having on the call itself.

My setup is as follows:
ServerA(Asterisk => External facing server connected to VoIP provider (Teliax) via IAX2 using G729 only and internal SIP phones via ulaw only.
ServerB(Asterisk => Internal server connected to all SIP phones using ulaw only.
ServerA and ServerB connected via IAX2 using ulaw only.

The message is appearing in the message log on ServerA

ServerA and ServerB are in two physically separate locations connected by a 50Mb/s microwave link.

An external outbound call would then look like:
EXTEN[XX] =>SIP(ulaw)=> ServerB =>IAX2(ulaw)=> ServerA =>IAX2(G729)=> Teliax

Am I still maintaining G729 compression on my IAX2 channel to Teliax?

Thanks for any insight you can provide,


It means that all the audio must pass through the core of Asterisk, because it has to be reformatted. Native bridging would have reduced the CPU load on Asterisk by even more than the reduction from not transcoding. At least for SIP, the audio might not even pass through the Asterisk machine.

You are still using G.729 to the right of server A.


Thank you for taking the time to reply and provide a little insight into what’s going on with my phone system. I guess it’s time for me to start digging a little deeper into Asterisk to learn more about what’s going on inside the server(s).

Thanks again,