My CUCM 7.1.3 is in US and trying to register few phones (7941, 7961, etc) from India but it is hanging in "registering" mode. When I go to the status messages on IP phone, I see CTL installed. I am able to see the Unified CM1 and Unified CM2 are pub and subscriber IP addresses. I didn't factory reset, manually provided IP addresses but no luck :-( There is a firewall between CUCM & IP Phones and I opened all the ports. IP communicator is registering fine without any issues. Can you please sugest?