Apparatus for providing telephone connection between one or more cellular radio telephones and a cellular radio switching system, comprises at least one moveable base transceiver station (511) for providing a radio connection with the cellular radio telephones, and having means for detecting whether the moveable base transceiver stations are in range of a fixed base transceiver station (543), and means for controlling the output of the moveable base transceiver stations (511) when such a fixed base transceiver station is detected such that transmissions from the moveable base stations do not interfere with transmissions from the fixed base station within a predetermined area surrounding the fixed base station (543). The system may also include a position finding system (590, 591), linked to the output control such that transmissions from the transmitter (511) cannot be detected within a predetermined area (T).