Hi Dustin,
This interface is only used in CCM to Legacy VM integrations (via SMDI) if you are not setup that way (which I don't think you are, using the "older SMDI integration) this is why you are seeing this behaviour :)
Cisco Messaging Interface Service
The Cisco Messaging Interface allows you to connect a simplified message desk interface (SMDI)-compliant external **Third Party** voice-mail system with the Cisco CallManager. The CMI service provides the communication between the voice-mail system and Cisco CallManager. The SMDI defines a way for a phone system to provide a voice-mail system with the information needed to intelligently process incoming calls.
Genrally the Cisco Messaging Interface (CMI) is a Cisco CallManager service that should be run only on the publisher server. This service intercepts calls destined for voicemail and generates appropriate SMDI messages, which are then delivered to one of the server's Component Object Model (COM) ports.
Hope this helps!
Rob