We have a Mitel 3000 system. While on "Night Service" or "Forward All Calls to Voice Mail," callers have the option of dialing an extension, it they choose not to, calls are dumped into the general voice mail box. The problem seems to be that if they hang up before the message is complete, the incoming lines ring back continually until somebody arrives in the morning. We have often arrived to have 3 lines ringing like this, but nobody is on the line (Caller ID still indicates the incoming phone call). How do I change it so that the system ends the call?