CME CUE codec

Unanswered Question
Feb 18th, 2008
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i have the following setup:

1) CME at the HQ

2) An Ip phone at remote branch is configured to register with the HQ CME, i have added the codec g729r8 under this ephone.

everything works fine when i call an ip phone at the HQ (G729 is showing as codec, i can see it with the help button on the 7940)

when i call the CUE i see that the codec is G711 and it works but it should be G729 right?

the transcoding is configured on the CME but not showing anything.

my question how can i force this remote phone to work as G729 withe CUE

Good day

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Rob Huffman Mon, 02/18/2008 - 09:34
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Hi Wissam,

CUE only does G711 so this would be expected behaviour. There is a need in this setup for local Transcoding.

Codecs and Transcoding

Cisco Unity Express supports only G.711 voice streams, so all calls made into the system (including those from IP phones, PSTN gateway ports and any other VoIP equipment in your network) must use G.711 if they enter the AA or voice mail pilot numbers that terminate on Cisco Unity Express.

If you require that G.729A calls traverse IP segments of your network between sites, and that these calls forward or dial direct into Cisco Unity Express AA or voice mail, then you must use a transcoding resource collocated with Cisco Unity Express to change the voice stream from G.729A to G.711 before the voice stream enters the AA or ***voice mail pilot numbers.

Hope this helps!


twissam Mon, 02/18/2008 - 11:11
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i am not sure if i got your answer, but i do have transcoding and i have forced the ephone to work g729 but still when calling the CUE it goes G711. (note that when i call another ip phone G729 is the codec)

i know that CUE only accepts G711 that's is why i have the transcoding configured but there still something missing, a mystery.

i can see it is a limitation, i mean when the ip phone sees the G711 he just use it and not the G729 instead of calling the transcoder.

I am just thinking loudly, but try it and you will see what i am talking about ;-)

thanks for your help.

Good day

twissam Sun, 03/09/2008 - 05:58
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just to let you know that the dspfarm assit was missing which did the JOB. in fact codec g729 works great to force calls between IP phones to be G729 but when it comes to having transcoding involved we need to include the assist

under ephone:

codec g729r8 dspfarm-assist

Good day

vinhnguyen Wed, 07/27/2011 - 05:24
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Hi All

From IP Phone across WAN into Unity Express the transcoding resource convert the G729 to G711.  However what happen to the prompt being played by Unity Express back to IP Phone.  Does the transcoding resource convert G711 back to G729 and send it back over the WAN?


Aaron Harrison Wed, 07/27/2011 - 05:46
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It's best to open a new thread if you have a new question rather than hijack a thread that is only vaguely related.

In answer to your question, transcoding works bidirectionally - that is, the stream in one direction is converted from G711 to G729, and from G729 to G711 in the other direction.



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