Yes, the first assigned VM port is used to send information from the processor to the messaging such as MW light on and off, night service on/off, time, etc. But the OP is not clear about the problem he is having. I understood him to say that when you log into a mailbox it will say "old messages" even though new ones have been left and they show up some time later.

If the MW light fails to indicate new messages until some time later but the messages are there then I would check the VM port assignments. But if it's the former, then there is some other problem and that's often cured by a reset.

-Hal