The Cisco Call manager is version 4.2 using a private network of IP addresses.
Regular IP phone calls are working well in every direction.
The problem that I'm experiencing, is when two people, connected via Cisco VPN and using the Cisco IP Communicator software are not able to hear each other at all. The phone call is normally established but the calling parties are not receiving any sound on both ends. Cisco IP communicator via VPN to a regular phone or office IP phone is working well.
My question is, where should I start debugging the problem (where is it most likely to find it) - Cisco VPN concentrators, Cisco call manager, the soft phones? Could it be a firewall issue too?
Thank you forward.