Well we aren't getting the disconnects, but the system just doesn't work well. The voicemail takes 10+ rings to pick up, if it ever does. I can leave a vm, but the handset never tells me I have one. The time is wrong on the messages left.
I've had secretaries say that they are trying to call another secretary, and that the phone rings and rings. They try to call again and the secretary said the phone never rang.

Just throwing these symptoms out there in case someone might recognize a problem. It's probably all configuration. Getting the tech out here to work on the system is half the battle...