Abstract: A method and device for achieving reliable prevention of cellular telephone calls, within a given area. In the preferred embodiment, the device and method operate to block the control frequencies of the cellular system within a given area. The device broadcasts a blocking signal with a low power output, which interferes with the reception ability and decoding of signals and commands broadcast at the control frequency. Thus, the handshake routine of the telephone/cellular subscriber with the local cellular system is prevented. Operation of the device is achieved in several ways, manually, automatically, and/or by remote control. Its operation prevents cellular communication ability by subscribers within the area or within the effective blocking range, which is derived from the effective radiated power (ERP) of the blocking signal, its type and the type of communications/or blocked system.