I'm running a Microsoft OCS R2 connected over SIP to a Cisco2821 running IOS 12.4.24T1 and a CCM running 4.0 connected to the same Cisco2821 over h323. Calls made from a Cisco Phone to OCS works fine, but it's not possible to establish a call from OCS to a Cisco Phone. The Cisco Phone is ringing, but when I pick up the phone, there is no voice and after about 7 seconds, the call is disconnected.
Any ideas?
Find attached the config of the Cisco2821 and the output of a debug ccsip messages.