Interactive television communication system

An interactive communication system, the system comprising a central controller, and at least one remote unit adapted to be connected to a display device, said central controller generating signals in accordance with a service function, access to all or part of which is restricted, the signals being supplied to said at least one remote unit for display on the display device, wherein said at least one remote unit includes a processor, responsive to signals from said central controller, and being selectively connectable to said central controller to transmit information back to the central controller, said at least one remote unit further comprising an input device and a control memory connected to said processor, said input device allowing a user to enter information, and said control memory storing access control data, the processor being responsive to the access control data to allow a user to gain access to the restricted part of the service function, and periodically supplying data to said central controller related to said access, wherein said central controller can generate signals which are supplied to said at least one remote unit to modify the access control data, and wherein said processor is adapted to modify the access control data in the control memory independently of said central controller to allow additional access.