We are trying to integrate Microsoft OCS 2007 with UCM 7.0(1) using SIP trunk. OCS does not have any PSTN gateways and everything from OCS is sent to UCM (except PC calls from one OCS client to another). The goals are:
1. Single Number Reach between IP extension and OCS client (using Cisco Mobility features)
2. Call signaling/establishment between Cisco and Microsoft IPT worlds.
After establishing SIP trunk between UCM and OCS Mediation Server both (1) and (2) above work, however there are certain things I see which do not work as expected and the most bizarre one is:
I initiate call from OCS client to PSTN destination through MGCP gateway registered to Call Manager. I answer PSTN phone and then hang up the call on OCS client. What happens is that my IP Phone "wakes up" and goes into Hold, playing MoH for the PSTN phone. It stays like that for 10-12 seconds and then the call ends. These 10-12 seconds are very consistent and it happens everytime. OCS client number is configured in Remote Destination Profile in UCM, which is assocated with my IP Phone DN...all part of Cisco Mobility setup.
It looks like SIP signaling issue, that whatever OCS signals to UCM for ending the call, is perceived by UCM as putting the call on hold for 10-12 seconds....
It resembles a bit of what happens if you have shared lines in Call Manager. If you answer a call on one device and then put the call on hold, the other device with that line will "wake up" and the call will appear to be on hold there as well, so it can be picked up from the other device. In this case OCS Client and IP Phone are not really shared lines, though Cisco Mobility makes SNR, so in a sense you can think about them as shared... But I am not putting the call on hold, I am hanging it up....
Did anyone see anything like that?