CUE and G.729

Unanswered Question
Nov 9th, 2007


have set up a CM4.2 with CME and CUE of a 256K WAN link (sorry thats the limit). Have an issue with the CUE codec. If a caller on the CM4 calls a user on the CME and then get put through to Voicemail the call is dropped using the G729 codec. If I change the setup to g711 then all is ok. Anyone got any idea how to change the codec presented to the CUE on the CME router. Its has to go 729 over the WAN because of the link size.



I have this problem too.
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Overall Rating: 4.7 (3 ratings)
Paolo Bevilacqua Fri, 11/09/2007 - 05:29


CUE does not support G.729, and cannot be changed or configured to do so.

You could use transcoding to convert codec, however it's a more advanced configurations, there are many threads about it on the forum.

rob.huffman Fri, 11/09/2007 - 05:34

Hi Paul,

Hope all is well with you :) This is surely a codec/transcoding issue here. CUE only does G711 and the calls are probably coming in G729a as you most correctly noted. 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!


EDIT: Hi Paolo, as always you beat me to the punch with your superior knowledge and typing skills :)

Paolo Bevilacqua Fri, 11/09/2007 - 05:55

Hi Rob,

Really, I'm neither fast nor more knowledgeable than you, I'm just more 'brief'.

Anedoctical story, once upon a time, I had a coworker, a very knowledgeable guy, named Curt. He was famous for his 'brief' answers, however when pressed, he would himself admit, that he was curt indeed :)

rob.huffman Fri, 11/09/2007 - 06:00

Beautiful!!! Great stuff Paolo. 5 points for your awesome participation here (and for a nice laugh today as well)

Take care my friend!


rob.huffman Fri, 11/09/2007 - 06:07

Hi Paul,

Thank you for the very kind words and nice rating as well :) It is always nice to hear from you again. Your reference to "digging" up docs around here is too true!

Take care,



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