Cisco Developer Community

Session Initiation Protocol (SIP) is a Internet Engineering Task Force (IETF) standard for multimedia communication and conferencing over IP. Telephone calls, video, instant messaging/presence, etc. can be supported.

SIP Trunk - Cisco Unified CallManager SIP Trunk signaling interfaces connect CallManager clusters with external SIP User Agents, such as SIP gateways, applications, and SIP proxy servers. Applications which handle SIP calls, but do not need to register SIP endpoints or use line-specific SIP features can be implemented using SIP trunks. SIP presence subscription (SIP/SIMPLE) is also supported via SIP trunks.

SIP Line - Cisco Unified CallManager SIP Line features provide SIP registration services, as well as SIP feature support for additional capabilities required by desktop phones/soft-phones.

SIP Transparency and Normalization - Cisco Unified Communications Manager and Session Management Edition provide a set of features called SIP Normalization and Transparency to customize SIP internetworking with external SIP providers. Normalization is the process of transforming inbound and outbound messages, while Transparency allows SIP information to be passed through from one call leg to another.  The Normalization and Transparency feature uses Lua scripts which are associated with SIP Trunks.  The scripts operate on inbound and/or outbound SIP messages. Almost any information in a SIP message can be transformed or passed through by SIP Normalization and Transparency.

Development Resources

Forums		SIP Line and SIP Trunk Developer Discussion Forum
Wiki		SIP Wiki
Documentation		Technical Documentation
Blogs		Messages from the Product Manager
Finding Help		Where to find help resolving issues