2.2.2.2 SIP URI Parameter Extensions for Contact, Route Header and Request-URI Fields

  • Article

The following SIP URI parameter extensions can be inserted by SIP elements into the URI of the Contact header field:

  • opaque-param

  • gruu-param

  • grid-param

  • ms-fe-param

  • ms-opaque-param

These extensions can then appear in the Request-URI field because, as specified in [RFC3261] section 12, the URI in the Contact header field is stored in the dialog state and is included as the Request-URI field of each SIP request within a dialog. Also, if the Contact header field is used in the REGISTER request, as described in [RFC3261] section 10, the Contact header field can be stored by the SIP location service and then used by the SIP proxy, as described in [RFC3261] section 16, to populate the Request-URI field. In addition, as described in [RFC3261] section 16.4, if the SIP element sending the request is a strict router, it can place the URI from the Contact header field into the Route header field.