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Calls taking G729

Hi All,

WE have Cisco 3925 Router with CME. We registered 2 IP soft phones and tried making calls,. Calls are working but takin G711. How to make sure that it takes G729 for both onnet and offnet calls.. I have given G729 as the first one in theVocie class codec preference, but stil it takes G711.

please help in this.

George Thomas

Have you specified the codec's under the dial-peers? Are you sure the calls are matching the dial peer you specified and not dial-peer 0? You could use debug voip ccapi inout to figure that out.

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Rising star

Hi there,

You can try setting 'Optimize for Low Bandwidth' under CIPC under Preferences > Audio.  However that puts the codec decision into the end users hands which isn't always the best idea.  You can try hard coding the codec on dial-peers as mentioned above (using voice-class codec) or you can specify the codec on the ephone for the CIPC as well.  You'll want to watch out for codec mismatches with other endpoints and dial-peers as well.



Im trying to understand why would specify a codec on a dial-peer when the phones are simply calling each other on the CME.

use the global command for this.  If you are using a trunk or dial-peer, then you can specify it there. 

Tthats correct Tom. I think it wont take any dial peer when 2 ip phones calling each other directly in CME. I tried by giving codec preference as G729 directly in the endpoint, but still having the issue..

Im still lost on what you are doing.  (2) phones on the *same* CME will not use a dial peer to call each other.


You can select the G.729r8 codec on a remote IP  phone to help save network bandwidth. The default codec is G.711 mu-law.  If you use the

codec g729r8 command without the  dspfarm-assist keyword,  the use of the G.729 codec is preserved only for calls between two  phones on the Cisco Unified CME router (such as between an IP phone and  another IP phone or between an IP phone and an FXS analog phone). The

codec g729r8 command has no affect on a call directed through a VoIP dial peer unless the dspfarm-assist keyword is also used.

To force Phones take G729 codec. Please use command under ephone prompt.

codec { g711ulaw | g722r64 | g729r8 [ dspfarm-assist ]} 

codec g729r8


Ronak Patel

Regards Ronak Patel Rate all helpful post by clicking stars below the answer.
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