Communication between two call managers

[Shimommm]

We have two call managers, one in a zone and the other one is in a different zone, between them is the ISA Server, it allows all protocols between the two call managers, there is a trunk (non-gatekeeper)between both call managers,the call setup is done successfully, but when trying to answer the ip phone the call drops!!!???

Anyone can help ??

 

[whykap]

It could be a codec issue. make sure that your codec is the same, if not that you have available transcoding.

 

[Shimommm]

The call managers are working correctly, and the call established successfully if we bypassed the ISA server, so I think that the problem is in the ISA, But we already open all protocols between the two call managers!!