I have started moving users to a new mailserver. The users on the new server receive their voicemail via exchange and can listen to it via the phone as well. The MWI on the phone however does no longer work.
We ran into the same thing....in Unity, user profiles show new mailserver and receive vm, but MWI flag isn't updating. MWI status in Unity says updating or something. From what I gathered, the official fix would be to use the Global Subscriber Manager in the Tools Depot to move the subscriber to the new server. This wasnt an option due to the following error:
"the commserver\Stream files directory is not shared properly"
To cut to the chase, what worked was a reboot of the Unity box! Note: I did try to run the permissions Wizzard first to add the new server relationship- maybe that was a preequisite before moving the mailboxes?