CUCM : How to Prioritize G711 A-Law over U-Law without TXCoder

Answered Question
Mar 22nd, 2012

Hello all,

I've read many post in this forum, and not found yet a way to prioritize the G711-A in the CUCM (6 or 8).

By default the CUCM use the G711U, and IP Phones also. All solution have to use a Transcoder even just interverting a codec :-(

Is there any way to confgure the CUCM to use the G711-A in the first preference thant G711-U, without using transcoder.

In the CME, we can do a voice class codec to build the preference. What is the equivalent of this in the CUCM.

The problem is that, when the IPPhone make a sullplementary service (Hold,...) the sent codec is a G711U. But the Trunk side want a G711A.

Thus result a connection problem.

Using a Transcoder (MTP) for more 1000 calls may give some problems to the CUCM and Vidéo calls.

Please help.

regards,

Antra

I have this problem too.
0 votes
Correct Answer by leemichaelj about 2 years 3 weeks ago

The section Gordon is talking about should be in the Regions section from the CallManager Service Parameters. i've just finished a 8.5 project where it was required to disable G.711 U-law to prevent the use of transcoders etc..

There is an option "G.711 mu-law Codec Enabled" and G.711 a-law Codec Enabled, its possible to disable G.711 mu-law completely in the cluster. But do need CUCM 8.5.

The section below is from the help text.

This parameter determines whether Cisco Unified Communications Manager (Unified CM) allows negotiation of the G.711 A-law audio codec for all, some, or no devices. This parameter applies to both the 64 kbps and 56 kbps versions of G.711 A-law. Valid values specify Enabled for All Devices (calls will be able to use the G.711 A-law codec), Enabled for All Devices Except Recording-Enabled Devices (calls involving recording-enabled devices will not be able to use the G.711 A-law codec), or Disabled (no calls will be able to use the G.711 A-law codec). The G.711 audio codec standard defines two different companding algorithms, mu-law and A-law, each of which is treated as a distinct codec. Another service parameter, G.711 mu-law Codec Enabled, controls the G.711 mu-law codec. You can use this parameter to disable G.711 A-law when you do not want G.711 A-law to be negotiated during a call. Disabling G.711 A-law means that it cannot be used for any call feature, including basic audio and video calls, transcoding, music on hold, announcements, ringback tones, and conferencing. When G.711 A-law is disabled, Unified CM will select the next preferred codec that both parties support (for example, G.729). If there are no other matching codecs between the two parties, Unified CM allocates a transcoder if one is available and if the transcoder is capable of transcoding between the codecs supported by the two parties. If the transcoder allocation fails, the call will fail. If G.711 A-law is the only codec supported by at least one party in a call, and the codec is disabled via this service parameter, then the call will fail. Because Unified CM prefers G.711 mu-law over G.711 A-law, disabling G.711 A-law alone has no effect on whether G.711 mu-law can be negotiated; disabling G.711 mu-law alone allows G.711 A-law to be negotiated rather than G.711 mu-law. To disable the G.711 codec entirely, set this service parameter and the G.711 mu-law Codec Enabled parameter to disabled.

Hope that helps?

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Paolo Bevilacqua Thu, 03/22/2012 - 02:32

If you use CUCM with a ITSP, you should have a CUBE as well. You configure anything there.

iantra123 Wed, 03/28/2012 - 01:06

Hi all,

Thanks for your help

I've used a CUBE and it seems working.

But the new problem is now the CPU on the router.

I'm using a 2811 with PVDM with 256MB of memory.

For 30 calls the CPU reach the 70-75%. Is it normal or not? Is there any document about sizing for CUBE?

the IOS is :c2800nm-adventerprisek9_ivs_li-mz.124-24.T5.bin

Regards,

Antra

Gordon Ross Thu, 03/22/2012 - 03:25

In later versions of CUCM, there are some options under Service Parameters to enable/disable G.711a & G.711u individually. I've been meaning to try these myself, but not got round to it yet.

(A while back, I thought I saw a parameter somewhere, which allowed you to choose whether G.711a or G.711u was the default codec. Can't find it now :-(  )

GTG

iantra123 Wed, 03/28/2012 - 01:13

Thank you Gordon,

I've searched it in the CUCM 6.0, and the section you're talking about is the Cisco IP Voice Media Streaming App.

It's let you choose the MoH codec.

regards,

Antra

Correct Answer
leemichaelj Wed, 03/28/2012 - 04:28

The section Gordon is talking about should be in the Regions section from the CallManager Service Parameters. i've just finished a 8.5 project where it was required to disable G.711 U-law to prevent the use of transcoders etc..

There is an option "G.711 mu-law Codec Enabled" and G.711 a-law Codec Enabled, its possible to disable G.711 mu-law completely in the cluster. But do need CUCM 8.5.

The section below is from the help text.

This parameter determines whether Cisco Unified Communications Manager (Unified CM) allows negotiation of the G.711 A-law audio codec for all, some, or no devices. This parameter applies to both the 64 kbps and 56 kbps versions of G.711 A-law. Valid values specify Enabled for All Devices (calls will be able to use the G.711 A-law codec), Enabled for All Devices Except Recording-Enabled Devices (calls involving recording-enabled devices will not be able to use the G.711 A-law codec), or Disabled (no calls will be able to use the G.711 A-law codec). The G.711 audio codec standard defines two different companding algorithms, mu-law and A-law, each of which is treated as a distinct codec. Another service parameter, G.711 mu-law Codec Enabled, controls the G.711 mu-law codec. You can use this parameter to disable G.711 A-law when you do not want G.711 A-law to be negotiated during a call. Disabling G.711 A-law means that it cannot be used for any call feature, including basic audio and video calls, transcoding, music on hold, announcements, ringback tones, and conferencing. When G.711 A-law is disabled, Unified CM will select the next preferred codec that both parties support (for example, G.729). If there are no other matching codecs between the two parties, Unified CM allocates a transcoder if one is available and if the transcoder is capable of transcoding between the codecs supported by the two parties. If the transcoder allocation fails, the call will fail. If G.711 A-law is the only codec supported by at least one party in a call, and the codec is disabled via this service parameter, then the call will fail. Because Unified CM prefers G.711 mu-law over G.711 A-law, disabling G.711 A-law alone has no effect on whether G.711 mu-law can be negotiated; disabling G.711 mu-law alone allows G.711 A-law to be negotiated rather than G.711 mu-law. To disable the G.711 codec entirely, set this service parameter and the G.711 mu-law Codec Enabled parameter to disabled.

Hope that helps?

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Posted March 22, 2012 at 1:54 AM
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