mgcp q931 channel B restarted

Unanswered Question
Aug 24th, 2009

Hi all,

Hi have install a cisco callmanager version 7.0.2 with a cisco 2821 mgcp pri controller gateway. The telco have provided a half E1 connection (time slots 1-15). The gateway successfully register with the callmanager and I'm able to establish voice calls. The problem is that the gateway/Callmanager from times to time (every minute) sends restart messages on different channels to Telco that clear the channel and the user must redial the number again to have audio. If we change to H323 the problem does not happened. Even when I don't have any calls the callmanager sends restart messages to the telco provider. On cco I have found a issue that could be related: CSCsx45587

CM :7.0.2

IOS: 12.4.22T


I have this problem too.
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Nicholas Matthews Mon, 08/24/2009 - 14:34

Try unchecking:

Inhibit restarts at PRI initialization

This will sometimes solve that problem. As well, partial PRIs aren't a very good idea with MGCP. There are some ways around it, but I think this may be your case:

Your provider sends STATUS or some other keepalive on channels 1-15. The gateway doesn't see anything on the other channels, and sends RESTART. If you look at the RESTART messages, they are probably for channels 16-23.

If you do want MGCP, either change the service parameters that busy them out on CUCM, or turn off 'ccm config'.


patcbr600 Mon, 08/24/2009 - 23:12

Hi Nick,

The problem is that the callmanager is sending the restart on channel 1-15 even when i have active calls on that channel.


Nicholas Matthews Tue, 08/25/2009 - 04:40

Hard to say - you may have isdn layer 2 problems. You can try debug isdn q921 to see if that helps, but I don't immediately know of any causes.


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