Patent ID: 7489659

Claim:
A communications system comprising: a) an Internet Protocol compatible communications network; b) a client device arranged in use to connect to said network in accordance with one of a plurality of communications standards and to change between said communications standards under predetermined circumstances; and c) a server arranged in use to couple to said network so to communicate with said client device, wherein said client device and said server are arranged in use to communicate at the network layer through an Internet Protocol tunneling technique, such that an Internet Protocol address of said client device remains the same during a handover from a first said communications standard to a second said communications standard, and wherein said Internet Protocol tunneling technique to form a tunnel encapsulates one Internet Protocol datagram within another Internet Protocol datagram, wherein said client device is automatically assigned a new Internet Protocol address during a vertical handover between two of said communications standards during inter-subnet roaming, and the tunnel is reconfigured by substituting a previous Internet Protocol address with the new Internet Protocol address; said client device using a direct connection to the server using the new Internet Protocol address to inform the server that the re-configuration of the tunnel is needed, and in response, said server re-configuring the tunnel so that configuration of said client device is entrusted to said server without placing requirements on access networks.