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New Member

MGCP and H.323 gateways not working together

We have a 3640 in Mexico defined to our Call Manager here in Atlanta as a H.323 gateway. Also in the same Call Manager is a T1 PRI defined to our PBX as a MGCP gateway. When people in Mexico call phones connected to our PBX we get one way conversations. We have a couple of other H.323 to MGCP gateways situations that don't work. It seems the two are not compatible. Has anyone else ran into this. If so, what was your solution.

Cisco Employee

Re: MGCP and H.323 gateways not working together

According to your description, I believe that you have a topology like the following diagram.


You didn't mentioned what type of circuit you had between the 3640 and the telco in Mexico or the type of gateway used for MGCP in Atlanta.

However, there should be no problems with this type of configuration causing one-way audio.

In this case CallManager talks H.323 to the 3640 in Mexico and talks MGCP to the gateway in Atlanta for the call control. When a call is placed from a PSTN phone in Mexico to a PBX phone in Atl, the call setup will first take place via H.323 between the 3640 and CCM and via MGCP b/w the Atl gw and CCM. After the call setup is complete, the audio stream should be connected directly between the 2 endpoints (ie 3640 gateway and the Atl gateway).

You should check for IP connectivity between the Mexico 3640 and the Atl router. Note, the call setup could complete successfully b/c both devices can reach the CCM, but can they reach each other when CCM steps out of the picture?

The following URL will also provide more good info on troubleshooting one-way audio.

Hope this helps.


New Member

Re: MGCP and H.323 gateways not working together

Shane thanks for the info. The actual setup is like this


The mex router has 12.1.2T.

The CallMgr has 3.1.4B.

The 4006 has 12.2.11T.

We can here Mex, they can't here us

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