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New Member

Call codec issue with G729

Dear Networkers,

We have a CUCM 8.5(1) cluster (1 PUB + 2 Subscribers).

We're using CIPCs only (Internal DNs 1XXX). we have an AS5350-XM [ IOS 15.1(1)T2 ] Voice Gateway with isdn links to the PSTN. We're using a very basic configuration.

we have the following call scenario : Agent Calls via CIPC PSTN number -> Route Pattern -> RouteList -> Route group -> H323 Gateway (AS5350-XM) -> Controller E1.

The issue is that the call leg between the CIPC and the VG is on G729 ! I don't know what happened and evry outgoing call through the Gateway is with G729 ! it was with G711 before !

CIPCs and Gateway are all in the same device pool. I checked and found that the VoIP dial-peer poiting to the CIPC extensions is already configured in the voice gateway and is using G711ulaw.

We made a CUMC packet capture and found that the Gateway is forcing the codec negociation to G729 !

Can you please advice ?

Thanks in advance.

Everyone's tags (3)
Cisco Employee

Call codec issue with G729

By any chance do you have the optimize for low BW option checked in the CIPCs?



if this helps, please rate



if this helps, please rate
New Member

Call codec issue with G729

Hi Jaime,

I have already checked this and it is unchecked

i made a packet capture from CUCM and saw that the VG is forcing the codec to G729 on the OLC (open logical channel) h323 signalling.

Didn't know why !

Any ideas ?

New Member

Call codec issue with G729


what is your configuration in voice port (E1) on VGW AS5350, and whats the capture between CIPC and VGW.


Sabah Awni

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