Abstract: In an electronic communication system, having a central transmitting station and N remote receiving stations, the central station sends out a signal train consisting of a wide reset or synchronizing pulse (R) and a series of N narrower time-sequenced or time-slotted clock pulses (C). An intermediate width station selector pulse (S) in the signal train designates a call to a particular remote station. The receiving stations are equipped to recognize, acknowledge and respond to the signal train in the correct fashion if in the calling mode or in the polling mode of operation.