CME with SIP trunk

[vanwitt]

Hi guys,

I have a CME configured with PSTN in G711 for all phones. Customer wants SIP trunk in G729. Could phones speak G711internally and G729 with SIP calls without involving DSP ressources?

[Ayodeji Okanlawon]

No,

You will need a transcoder. If you hardcode the dial-peer to g729 and set the phones to only do g711...

Please rate all useful posts

"opportunity is a haughty goddess who waste no time with those who are unprepared"

[danplacek]

aokanlawon: Perhaps I am mistaken, but isn't G711 the default codec on the phones anyway... but if the incoming SIP calls are G729, the phones should still be able to accept the call without transcoding?

I was not aware of any restriction on mixing codecs, is there documentation on this?

Thanks.

[Ayodeji Okanlawon]

Daniel,

Even though cisco phones support both codecs, they can only work with what is offered/supported. In this scenario one leg can only support one codec and the other leg a different codec, hence a xcoder will be needed..

A simila thread is covered on the forum here..

https://supportforums.cisco.com/thread/2172529

The only work around is to configure a voice class codec with both g711 and g729 on the dial-peer..And in this case g711 will be used for the call.

Here is the scenario...

Sip provider advitises

Please rate all useful posts

"opportunity is a haughty goddess who waste no time with those who are unprepared"

[vanwitt]

Ok, so with CME cisco phones cańt support G711 and G729 depending on the origin of the call? So i can set my phones to use G729 and so only transcode to access CUE?

[Ayodeji Okanlawon]

100% correct.

Below is a similar thread where G729 was used on the phone and xcoder used to talk to CUE

https://supportforums.cisco.com/thread/298808

Please rate all useful posts

"opportunity is a haughty goddess who waste no time with those who are unprepared"

[vanwitt]

Phones dońt support the 2codecs simultaneously?