Blackberry devices are JAVA based and do NOT use Windows Mobile.
However, there is an "add-on" for Windows Mobile called "Blackberry Connect" that allows a Windows Mobile connected to a Blackberry Enterprise Server.
Now if a user wants to receive voicemails on their Blackberry, they will need a late model device with Blackberry firmware 4.2 in order to play back the messages. On the Blackberry devices, just set it up for IMAP and point it to the Unified Messaging Server. It will then just poll the mailbox about every 15 minutes for new messages.
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