One side can initiate the call while other side cannot

[muhammad.shah]

From the Main Campus call cannot be initiated whereas from the branch side call can be initiated. Moreover, we are also observing spoofing on the interface of the Main Campus router

[TONY SMITH]

Can you post debug "debug isdn q931" output for a good call and a bad one.  Then we'll need to get some more detail about the rest of your system.  

[Nithin Eluvathingal]

As @TONY SMITH mentioned share the debug isdn q931 from main campus and branch. Also can you explain a little more about your UC infrastructure. And also more information about the call flow.

2.12.0.0