All protocols require that either a signaling interface (trunk) or a gateway be created to accept and originate calls. For SIP, the user must configure a SIP trunk. SIP trunks connect Cisco Unified Communications Manager networks and SIP networks that are served by a SIP proxy server. As with other protocols, SIP components fit under the device layer of Cisco Unified Communications Manager architecture. As is true for the H.323 protocol, you can configure multiple logical SIP trunks in the Cisco Unified Communications Manager database and associated with route groups, route lists, and route patterns.

Supported Cisco Unified IP Phones (SCCP and SIP)

7971G-GE, 7970G, 7961G-GE, 7961G, 7941G-GE, 7941G, 7911G, 7906G

Supported Cisco Unified IP Phones (SCCP only)

7931G .

For further information click this link.

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/rel_notes/6_0_1/cucm-rel_note-601b.html#wp46083