When the IMS-ALG requests an IMS-AGW to perform a registration (see clauses 6.1.3, 6.1.4 and 6.1.7), the IMS-AGW performs a re-registration to the IMS-ALG which is defined in the IMS-ALG address.
The IMS-ALG may request the IMS-AGW to report the current values assigned to distinct objects in the IMS-AGW. This procedure may be used when a change has occurred in the IMS-ALG such that the IMS-ALG is unsure of the current Service State of Terminations.
The IMS-ALG may use the Audit Value and/or Audit Capability procedures to obtain further information, about the objects whose capabilities have changed.
If an IMS-ALG discovers that it wants to go out of service it may start an IMS-ALG Out of Service procedure. The IMS-ALG can indicate whether it requires the context to be cleared immediately (forced) or cleared as the bearer control protocol clears the bearer (Graceful).