Registration Event Package Extension for Session Initiation Protocol (SIP) Globally Routable User Agent URIs (GRUU)
RFC 3680 defines a Session Initiation Protocol (SIP) event package for registration state. This package allows a watcher to learn about information stored by a SIP registrar, including its registered contact. However, the registered contact is frequently unreachable and thus not useful for watchers. The Globally Routable User Agent URI (GRUU) has been defined for SIP as a URI that is capable of reaching a particular contact, however this URI is not present in the format defined in RFC 3680. This specification defines an extension to the registration event package to include a GRUU.