The soft phones (I'm assuming CIPC or IP Communicator) is supposed to take the IP address of your PC which at that point, your PC is connecting to the VPN and has a different IP if is being masked to. When the soft phone registers, it should be registering with something within the VPN IP address that was assigned to your PC.
If the phone is not using VPN to communicate out, what IP address information is it getting? Is the phone registered to the CUCM and what IP address does it show it registering as in CUCM?
