The SIP trunk integration is a method to establish communication between Unity Connection and Cisco Unified CM using SIP protocol.

For a list of supported versions of Cisco Unified CM that are qualified to integrate with Cisco Unity Connection through a SIP trunk, see the Compatibility Matrix for Cisco Unity Connection at http://www.cisco.com/c/en/us/support/unified-communications/unity-connection/products-device-support-tables-list.html.

The Cisco Unified CM SIP trunk integration with Cisco Unity Connection provides the following features:

• Call forward to personal greeting

• Call forward to busy greeting

• Caller ID

• Easy message access (a user can retrieve messages without entering an ID; Cisco Unity Connection identifies a user based on the extension from which the call originated; a password may be required)

• Identified user messaging (Cisco Unity Connection automatically identifies a user who leaves a message during a forwarded internal call, based on the extension from which the call originated)

• Message waiting indication (MWI)

Unity Connection can be integrated with two or more phone systems at one time. For information on the maximum supported combinations and instructions for integrating Unity Connection with multiple phone systems, see the Multiple Phone System Integration Guide for Cisco Unity Connection Release 15 at https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/integration/multiple/b_cuc15intmultiple.html.

Unity Connection supports centralized voice messaging through the phone system, which supports various inter-phone system networking protocols including proprietary protocols, such as Avaya DCS, Nortel MCDN, or Siemens CorNet, and standards-based protocols, such as QSIG or DPNSS. Note that centralized voice messaging is a function of the phone system and its inter-phone system networking, not voicemail. Unity Connection supports centralized voice messaging as long as the phone system and its inter-phone system networking are properly configured. For details, see the “Centralized Voice Messaging” section in the “Integrating Cisco Unity Connection with the Phone System” chapter of the Design Guide for Cisco Unity Connection, Release 15 at https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/design/guide/b_15cucdg.html.