The local call manager registration status with the Gatekeeper.
The status changes from unknown to registered when the local
call manager successfully registers itself with the gatekeeper.
unknown: The registration status of the call manager
with the gatekeeper is unknown
registered: The local call manager has registered with
the gatekeeper successfully
unregistered: The local call manager is no longer
registered with the gatekeeper
rejected: Registration request from the local call
manager was rejected by the gatekeeper.