Partial dropped calls!?

[cartoondog1]

Using a VPN between sites, and it seems when either side initates a call all is good. 30sec into the call (most of the time, seems less likely to happen during off peak hrs) the remote branch site (site without the CM) can be heard by the Main branch party, but the remote branch party cannot hear what the main branch person is saying. Call is not dropped.

Any ideas where to start looking or how to trace? It is readily repeatable. All sites are using T1s and have minimal VOIP traffic. Typically one call concurrently going to branch locations. What I guess I am looking for are trouble shooting steps.

ICS 7750
CIsco CM 3.3.1
Phones 7960
Routers 2600

Thanks.

 

[tharder]

You say all is good. Are you saying the call gets set up ok but you only get audio in one direction or sometimes it ALL works and sometimes not.

We had issues with CME on our 2800 routers setting up a call but not passing audio in one direction. Opened a TAC case and Cisco said to upgrade them to 12.4(4)XC / CME 4.0(1).

It solved our problem. They said it had something to do with the VPN tunnel blocking the traffic in one direction.