A radio paging system, comprising a transmitting base station and a paging receiver with a battery-saving function. The paging receiver operates intermittently at different repetition periods, depending on the call traffic density. When there are fewer calls, the receiver operates less frequently, in order to avoid unnecessary operation and consequent battery drain. When there is a call to be sent, the period between attempted detections of a preamble code word is shortened. The receivers then lengthen the period for detecting a message, and receive a sync code word, followed by an address code word, which alerts the particular receiver being paged, an alert tone being generated. The message ends with a battery saving code word and ending code word. The battery saving code word alerts the receivers to lengthen the period between attempted detections of the preamble code word. The variation in length of periods between attempted detection is a battery-saving feature.