You want to use Exchange UM as the voicemail or you want to have UM features while using Avaya's voicemail that is integrated with Exchange?
Voicemail Pro will utilize the Exchange message store for voicemail storage and synchorize voicemail/email and telephone message waiting lights if that is what you are asking.
If you want to know if you can utilize the Exhchange UM feature with IP Office then yes although it is not officially supported and you will need a gateway from Audiocodes or Dialogic and trust me you want it to be T1 not analog. I've done it using other products as well but you'll be on your own to figure those out.
Kyle Holladay
ACSS & APSS SME Communications
MCP/MCTS Exchange 2007
Adtran ATSA, Aruba ACMA
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