US Patent 7342905 Communications system

A communications system includes a subnetwork connected to a network. The network has a first part and a second part, with the first and second parts being connected so that a first user can communicate with a second user. The first user is able to move within the respective part of the system. The subsystem includes a gateway for permitting communications between first and second parts. The gateway includes a register for storing information associating the first and second users, and for storing information relating to the current location of the first user so that information from the second user can be directed to the first user.