3.1 Common Details

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Endpoint Identification Extensions

This protocol provides several mechanisms for identification of SIP endpoints. These mechanisms produce an identifier that carries some or all of the following properties:

  • Long-lived: Can persist across device, application, or server shutdowns.

  • Distinguishes a specific instance: Can distinguish a specific endpoint among several endpoints that share the same user or service or application address-of-record to maintain per-endpoint state, such as security association (SA), registration state, and presence state, in various SIP elements.

  • Routes to specific instance: Can be used to address calls to a specific SIP endpoint among several endpoints that share the same user or service or application address-of-record event outside of the SIP transaction.

To maintain compliance with this protocol, the user agent MUST use one of the mechanisms described in sections 3.2, 3.3, and 3.4 to identify each SIP endpoint that it represents.