US Patent 7925762 Roaming support method and systems in UMTS

The invention relates to a communication method and system wherein a network element of a roaming user is attachable to a visited first network and be served by a serving means of the home network. When the network element of the roaming user is registering or initiating a connection to a called network element of the visited network, a network element of the visited network, such as proxy means, either adds information on the called network element or on a service element of the visited network when sending a message to the home network. The message is preferably sent as a protocol message, in particular a message of the Session Initiation Protocol.