Abstract: A pager system includes a transmitter with a control unit for selectively transmitting radio signals having specific pager codes, and a plurality of portable pager receivers each having its own electrical energy source and adapted to respond to a specific pager code. The pager system further includes a central unit coupled to the control unit. The central unit includes a comparing unit and is coupled to a first memory for storing information relating to the individual pager receivers, a second memory for storing reference data, a clock, and a presentation unit. The comparing unit compares the contents of the first and second memories for a specific receiver and clock data, and signals the transmitter when a code signal is needed. The presentation unit generates a warning signal in response to a code signal received from the transmitter.