A battery-driven modem contained in a housing ... fitted with four LEDs which indicate call status, speed, carrier frequency and battery depletion. The modem also has a data connector, telephone connections, acoustic-coupler connection and standardized miniature telephone jack. The modem is used for asynchronous data transmission between automatic data processing equipment via telephone lines in full duplex and acoustic-coupler mode at a speed of 300 or 1200 bits per second.
