4 Track Play /2 Track RecordTape all your telephone calls automatically. Starts and stops recording by detection of voice or sound. Perfect for use on single or multiline systems. Records all conversations from any extension on single line phones. Optional beep tone every15 seconds acknowledges you are recording the telephone conversation. Sound monitor switch lets you listen to conversations as they are being recorded.Simple installation. Req. 4AA batteries (not included) 90 day warranty.