This PBX configuration note contains information about deploying Exchange 2007 UM with a Cisco Call Manager 5.1 using direct SIP connection. You can use it to help decide if Exchange 2007 UM is the appropriate solution for your organization.
You can get it here: http://www.microsoft.com/downloads/details.aspx?familyid=68b43d3c-7c84-4c2f-bfd7-98754970d70e&displaylang=en&tm
Technorati : Cisco Call Manager, Exchange Server 2007, PBX, Unified Messaging
Del.icio.us : Cisco Call Manager, Exchange Server 2007, PBX, Unified Messaging