You can integrate CUCM and Exchange to have UM. You need to configure a SIP trunk between these two servers. On the
CUCM side, you can configure a SIP trunk as described on the following document:
-> Trunk Configuration
On the Exchange side, you need to refer to MS:
--> Microsoft Exchange 2010 Unified Messaging PBX Configuration Note for Cisco Unified Communications Manager 7.0
Attached are some screenshots on how to configure this on the Exchange.
Unified Communications PDI Team