A secure entry system (10, 44, 50, 60) makes use of radio transmissions to communicate with locks (12, 12' ), keys (46), and related components throughout the system. The radio transmissions can be made using a paging system, a cellular telephone system (52, 54), or any other RF carrier (26). Some embodiments (50) employ a cellular telephone (52) in lieu of an electronic key (46). Others integrate a paging receiver (14) within an electronic key to provide a unit with dual functionality. The system is illustrated with reference to exemplary applications in the industrial site security, real estate lockbox, and transportation fields (60).