Are all of your users (and yourself) using the same VPN profile? If not do all the profiles hand out the same routes? Once the CCM is done processing your call and providing you tone it directs you to one of the gateways on your network (something connected to the PSTN). This could be a VG, a 2800 or 3800, or a number of other devices with a PRI or POTS connection. All the RTP traffic is between you and the gateway (or you and another user on the network if they're in the office). The CCM only sets up the call. Can you access the gateway from your laptop when you VPN in? If not then that's your problem.
What does your client VPN terminate on? I'm not sure if you can terminate a client VPN on the gateway device. If the gateway is beyond your VPN termination point then perhaps you're in the situation where unencrypted traffic can't be routed back out the interface that the encrypted traffic just came in on. For example:
You Internet Border RTR/VoIP Gateway Pix CCM
In this scenario lets assume that the Pix is running a pre-7.x code. You can't access the VoIP gateway in this scenario because of the problem routing unencrypted traffic back out the interface that the encrypted traffic just came in on. 7.x introduced a way around this problem however. There are a couple of ideas to try.
As always call TAC. They are most helpful.