This Wireless Doorbell Signaler does not have to be wired into the existing doorbell. It is used in place of the existing doorbell for quick and simple setup. Simply hang the sensor on the door or on the wall near the door. Then plug the signaler into a wall outlet and plug a lamp into the signaler. When a guest presses the button on the sensor the signaler will notify you by flashing the lamp. With the purchase of an additional transmitter, the signaler can flash differently for front door, back door, and intercom.