Cisco Call Manager 4.x is now supported for integration with Exchange UM. That's right you can now integrate your CCM without upgrading to your infrastructure saving lots of money and including new features like:
Embedded Auto Attendants
IVR for integration with Calendar and Contacts
Single Message Store reducing licensing and infrastructure cost
Single Directory which reduces administration overhead.
For all updated info on integration with Exchange UM check out the Telephony Advisor -
The config notes for configuring Cisco Call Manager and Audiocodes via IP-to-IP SIP Trunking.
from the notes....When Cisco CallManager Version 4.x is implemented alone (i.e., directly interfacing) with Exchange Server 2007, certain Exchange Server 2007 functionalities are not supported such as Auto-Attended, MWI, and T.38 fax transport mode. Therefore, Cisco CallManager version 4.x suffers feature limitations when operating with Exchange Server 2007. Upgrade to Cisco CallManager Version 6.x seems to resolve these issues, but the trade-off is an extremely costly investment.