Leaving messages for non-UM-enabled users

Recently I got a good question from a coworker. He was working with a customer who was piloting Exchange Unified Messaging, and the customer was a little confused by a poorly-documented behavior of Exchange UM.

Consider that you have four test users who are UM-enabled: Alex, Brian, Carole, and David. You also have four users with Exchange mailboxes who are not UM-enabled: Magdalena, Nick, Oscar, and Pete.

The customer reported that he could dial the default automated attendant, or into Outlook Voice Access, and use dial by name to call Alex, Brian, Carole, or David.

However, he had Exchange configured to allow callers to leave voice mail messages without ringing the phone first (what I call “the coward setting”; it’s controlled with Set-UMDialPlan –SendVoiceMsgEnabled:$false). He was able to leave messages for Magdalena and the other non-UM-enabled users, which surprised him and generated the question.

This does seem odd. It’s easy to understand why you can leave a message for the first four users: they are UM-enabled, so they have extensions to which Exchange can transfer the call. But why can you leave a UM message for a user who isn’t UM-enabled? It’s because leaving a voice mail directly for a user doesn’t involve ringing an extension, so not having an extension assigned isn’t an obstacle. When you select that user for a message, UM will play the greeting (which is almost certainly going to be the system-generated TTS version of the user name, as a non-UM-enabled user probably will not have recorded a greeting) and record the message, then deliver it through the standard path.

The More You Know…