SIP Record-Route

In some cases, it may be useful for proxies in the SIP signaling path to see all the messaging between the endpoints for the duration of the session.


For example, if the biloxi.com proxy server wished to remain in the SIP messaging path beyond the initial INVITE, it would add to the INVITE a required routing header field known as Record-Route that contained a URI resolving to the hostname or IP address of the proxy.

This capability is frequently used for proxies that are providing mid-call features.

A route set is a collection of ordered SIP or SIPS URI which represent a list of proxies that must be traversed when sending a particular request. A route set can be learned, through headers like Record-Route, or it can be configured.