At site #1 we have a CUCM and a Voice Gateway, the gateway is a 2811 and is acting as the voice gateway as well as the VPN/Internet termination device. The tunnel to the remote sites is created from that 2811.
At site #2 there is a 2651XM terminating the internet and tunnell, but it is not working as a gateway.
The telephones at site 2 have 2 problems that are very strange
1) When the phones ring at that site, when you press Answer, there is a 2 second delay between the time they press answer and the time the speech path is created between the 2 phones
2) When a call is sent from the PSTN gateway to the remote telephone (say when unity transferrs a call to that user) the person presses answer and the call is just dropped (Fast busy to the caller). The gateway is setup as H.323 and I have bound the H.323 process to the INSIDE address.
The weird delay gets me because once the call is actually setup (G.711) the call sounds perfect, I spoke for 10 minutes with the remote end and didn't lose a single packet, MOS scores of 4.3 or better and the call was perfect which leads me to believe the VPN performance is good enough for bearer traffic, control traffic should be just fine.
update: For a laugh I enabled the MTP on the gateway in CUCM, I am using a hardware MTP in the 2811. When I do that, the PSTN calls are now flowing properly to the remote side in regards to bearer traffic -- delays obviously are still there.