mgcp gateway one way audio

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Jun 5th, 2008
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Have a 2851 running 12.4.18 spservices.

two pris one used primary for outbound one for inbound. Have intermittent issue with one way audio when ip phone dial out to the pstn. Does not happen all the time and if the person hangs up and calls back will work fine again. Pulling my hair out.

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Zin.Karzazi Thu, 06/05/2008 - 07:26
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We had a simulare issue, i went trough all cisco docs on this issue and nothing helped, we finally switched to H323 and the problem went away.

What you can do, is to go through this doc:

if it doesnt help, start some debugging on your gateway: debug mgcp packets and the like. try to hold the call you experience one way voice problem with and resume again see if that help. Phone firmware could also lead to such issue.


maharris Thu, 06/05/2008 - 08:22
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While persistent one way audio is almost always routing or packet delivery issues, we have had a number of cases where occasional one way audio like this has been flaky dsps, or dspware on the router causing issues. A lot of times a router reboot will clear it up for a while, and then it comes back.

Mary Beth

danny.howard Thu, 06/05/2008 - 13:02
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Ensure you have the following command:-

mgcp bind media source-interface FastEthernet0/0

toormehdi Fri, 06/20/2008 - 17:30
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yes thats correct.

u need to bind your control and media source to a routable/reachable IP.

If you have loopback interface with an IP which is non routable, you maybe sourcing your mgcp audio via that....and UCM may not be able to return it back.

Its good to explicity define control and media source for mgcp


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