I have a CUCM 6.1(2) cluster with two CUBE (h323 to SIP) routers. CUCM handles all PSTN routing for OCS. Everything works fine except if an OCS endpoint forwards calls back to the PSTN. If the call is forwarded to a land line phone, the call completes correctly. If the call is forwarded to a mobile phone, the call times out and fails. We can see the ISDN timer expirey message in the Q931 message on the originating PSTN leg of the call. It looks like neither of these calls sends a call progress message but since the land line call sets up quicker, the timer does not expire before the call connects. Anyone know how I can force either CUCM, CUBE or OCS to send a call progress message on a forwarded call?
Call flow is as follows:
MGCP PRI --> CUCM --> CUBE1 --> OCS --> CUBE2 --> CUCM --> MGCP PRI
Any help is greatly appreciated.