Requires no wires - installs in seconds! Button mounts outside door. Signaler box is plugged into an electrical outlet inside, and the attached line cord is plugged into a phone jack. An outlet on the signaler allows a signal lamp to be plugged in at that location, plus it will signal all remote receivers when the doorbell is pressed or the phone rings. Selectable flash code for front and back door or intercom (intercom requires additional sensor sold separately). Built in audible chime can be turned off.