a selector circuit is arranged between a telecommunication subscriber line and a telephone set and a facsimile device . the selector circuit includes a tone detector and a voice detector and circuitry for connecting the subscriber line to the telephone set or the facsimile device depending on the output of the voice detector alone or the outputs of both the voice and tone detectors . in a first state , known as telephone priority , the selector circuit responds to an incoming call by sending a return message as to whether facsimile transmission is desired . the tone and voice detectors are then activated , and if either a voice signal or a tone signal is detected , the selector circuit connects the subscriber line to the facsimile device . otherwise , the subscriber line is connected to the telephone set . in a second state , known as facsimile priority , the selector circuit responds to an incoming call by sending a return message as to whether telephone communications are desired . the voice detector is then activated , and if a voice signal is detected , the selector circuit connects the subscriber line to the telephone set . otherwise , the subscriber line is connected to the facsimile device .