We have SIP Trunks between our CUCM v7.1.3 and IPC Unigy system. All test calls to and from CUCM 7.1.3 and IPC Unigy working fine but have found when dialling from IPC Unigy to either Unity Connection 9.x or UCCX 7.x, the call rings without being answered. Believe it is something to do with the out-of-band signalling either not being present, or being present when it shouldn't.
Having difficulty tracing calls in log files.
Dialling from Unigy to either Unity Connection or UCCX via public telephone network call is answered ok.