Channel allocation method and apparatus

A method for authenticating terminals in a wireless communication service involves receiving registration requests from terminals requiring access, transmitting to each of the terminals a signalling channel assignment signal allocating a duplex signalling channel uniquely to each terminal, transmitting in the signalling channel an authentication request signal, receiving an authentication response signal in the channel, the contents of which depend on the context of the authentication request signal, and deciding whether to allow access to the system according to the contents of the authentication response signal.