I had an issue where a particular user’s voicemail on Exchange 2010 wasn’t working. When they called the voicemail number, they were asked “To access your mailbox, please enter the extension” rather than being greeted with their name and messages. The user was on Lync 2010, and Unified Messaging was enabled on their account with the matching extension number. Also, when dialing voicemail and trying to enter the extension number just met the message ‘XXX isn’t a valid mailbox’.
Disabling and re-enabling Unified Messaging made no difference. I was rather confident this was an Exchange/Unified Messaging issue, so I had the idea of checking ADSI edit to see if UM was properly enabled.
Checking the attribute “msExchUMEnabledFlags” found the issue. When a user has UM enabled, the value of this field should be 831, or 830 when disabled. I’ve come across this issue before, where it’s the wrong value and needs to be changed, but this was the first time I’d come across it as being 832.
Never a good sign when you google something, and you get zero results:
Changing the Attribute value back to 831 instantly fixed the issue, didn’t even require disabling and re-enabling Unified Messaging. If all else fails, change the value back to 830, refresh your Exchange Management Console and the user should show as being disabled for Unified Messaging, then re-enable as you normally would.
Hope this helps anyone else who comes across a similar issue.