Before you install the Unified Messaging Role in Exchange 2007, you’ll need to have the following updates already installed.

Windows Media Encoder 9 Series x64 Edition
Fix KB917312. Info on fix here.

All of the system and role requirements are listed in the Exchange 2007 System Requirements document.

After the UM role is setup, you can enable integration with Office Communications Server 2007 by running “exchucutil.ps1″ from the scripts directory of your Exchange 2007 install media/directory.  Run this from the Exchange Management Shell.  Then reboot your OCS server. Verify all is working by looking at the events with source “OCS Exchange Unified Messaging Routing” in the OCS category in your Event Log.

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