Abstract: A low-power, integrated coin acceptor for a payphone containing audit circuitry is described. The integrated coin acceptor connects to the telephone tip, ring and ground lines and connects to a dumb or smart payphone chassis to provide both coin validation and audit functions. The integrated coin acceptor is compatible with the audit software used by the central office, and assures a seamless transition between coin acceptor operation, audit data recording and audit information transmission. Components related to the audit function include a line interface to the tip, ring, and ground lines, a DTMF transceiver, battery backed-up RAM memory, EEPROM memory, real time clock, and battery and control circuits for data retention. During audit interrogation activity, the integrated coin acceptor takes control of the phone line, but contains circuitry that will return dial-tone to the user if an off-hook event occurs.