Explanation/Reference:
Explanation:
The deployment of a Unified CM Session Management Edition enables commonly used applications, such as conferencing or videoconferencing to connect directly to the session management cluster, which reduces the overhead of managing multiple trunks to leaf systems.
Unified CM Session Management Edition supports the following applications:
* Unity, Unity Connection

* Meeting Place, Meeting Place Express

* SIP and H.323-based video conferencing systems

* Third Party voice mail systems

* Fax servers

* Cisco Unified Mobility

The following applications must connect to the leaf cluster:
* Unified Contact Centre, CUCM, Unified Contact Centre Express

* Cisco Unified Presence Server

* Attendant Console

* Manager Assistant

* IP IVR

* Cisco Voice Portal

References: http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/session_mgmt/deploy/8_5_1/ overview.html