Improvements in, or relating to, mobile communication

摘要

The network has several base stations each serving several mobile telephone handsets (2) and connected to a public telephone network. A network server (4) supplies data to a network user. A mobile data unit (6) has a mobile telephone handset and data telephone equipment (5), and signalling circuits which, in response to the network user, transmit client attach detach signals to the network to inform the server whether the mobile unit is ready to receive and transmit data. The signalling circuits of the mobile data unit transmit the client attach and detach signals on the initiative of the user, in accordance with the OSI model at a level higher than layer three. The transmission of the client attach and detect signals is independent of the type of carrier network used and the type of access network used.