CUCM6.1 XCoder Failure

[Chuan Liu]

Hi,

I have a remote site configured to use g729 over the WAN. DSP xcoder resources from a 2811 are registered in CM. Revelant MRG and MRGL are configured and applied to the remote device pool. In the remote region, when I specify g729 as the codec to gateway region, all calls to PSTN fail. When the codec is g711, all work fine. I guess this is the xcoder failure, but do not know how to troubleshoot this.

Note: In the SCCP configuration command for XCODER registration to CM, there is no option to specify the ccm 6.1 version. The latest version available is 4.1. Does this matter? But it shows registered in CCM6.1.

Thanks for any advice.

[allan.thomas · Accepted solution]

I'm not sure if I have fully understood your scenario, what it not clear is where the PSTN gateway is located?

You have a remote site which uses G.729 across the WAN, you then mention that you specify G.729 as the codec to the PSTN gateway region? PSTN gateway and remote site in different locations?

If the PSTN is at the remote site, then you do not need to use G.729. You should configure the gateway endpoint and phones in the same device-pool which uses the same region, and configure that remote site region to use G.711 within itself and to others G.729.

If this is not the case and the PSTN is not local to the remote site, but over the WAN then the xcoders should be provisioned at the central site for the PSTN gateway.

Hope this helps.

Allan.

[Chuan Liu]

Thank Allan,

The PSTN gateway is located in central site and in different region. I have not provisioned the xcoders for the gateway. I will try that after hours and post the results.

Thanks again.

[Chuan Liu]

Hi Allan,

Yes, the XCODER is working now when I provisioned it on the PSTN gateway.

I have new issues now. When the new MRGL is assinged to the gateway, all outgoing calls (even when use g.711) will use the DSP XCODER, and I do not have enough DSP. Can I control that only phones in certain remote sites can make use of the hardware resources when they make outgoing calls?

Thanks.

[allan.thomas · Accepted solution]

Unfortunately it is not possible to provide that level of graularity :(

This is the problem commonly faced when provisioning PSTN breakout over the WAN, one thing you have not mentioned is whether the gateway is configured for MGCP or H323?

The dilema is whether you want calls from your Central site IP Phones to use G.711 or G.729?

By default MGCP gateway uses G711 when MGCP is enable, however it is possible to change the codec type 'mgcp codec'. Or with H323, you simply config codec preferences which are assigned to the outbound POTs dial-peer.

This may provide you with G729 end-to-end, but this may have an impact on other applications which only support G711, so you have be very cautious in your approach. Either way you will still require transcoding.

The safest option is to configure your Regions so that you remote sites carry on using G729, and that the Central site Region and the Gateway Region use G711 between each other. This will limit only the Remote Sites to transcoding.

One other concern is emergency calls? Have you given consideration to these when your remote site does not have local breakout.

Hope this helps.

Allan.

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