Humm.......
Ok, this is just a theroy. When the 3300's talk to each other, it's talking via UDP meaning that the PBX will throw a IP packet over the fence and really not care if it got it or not. A possibility is this: The IP phone sends a packet saying to ring VM. The 3300 sends a packet to the phone telling the phone (or other 3300) to play ring back. The vm answers and the 3300 sends a connect message. Now if that message gets dropped perhaps the audio stream would still be connected but the phone doesn't know it.
Just a theroy and I admin I'm grasping a straws and no doubt I'm confusing some Cisco CM stuff. You may want to check your network between sites. Check all your data switch interfaces for error and perhaps even do a ping test with a load. (ping <IP address> -t -l 80) Let it run for a bit to see if you drop packets.
Some more questions:
Are the callers always originating on trunks or also IP phones accross the net?
Which system is the call originating from?
What happens if you call a phone with the problem from one of the other switches?
When was the last time you rebooted both systems?
Ralph
www.aavoicepro.com/checkpoint