[Asterisk-Users] Message Waiting

[Daryll Strauss]

I've noticed a similar problem. I've got an inline caller-id box that
shows message waiting and an analog phone that shows the number of new
and old messages. They both continue to show message waiting even
after I've listened to and deleted the messages.

So it looks like Asterisk isn't clearing the message waiting light.
That would explain why your GrandStream is flashing as well.

- |Daryll