Turn on a light, activate a camera, or initiate a security system when someone pushes the door intercom button on your Doorbell Fon Intercom System. This Doorchime Interface Module provides momentary dry contact contact closure which can then be tied into a security system, automation system or any other devices that are looking for a momentary contact closure. Devices connects to the Doorbell Fon controller box and requires two AA batteries (included).The Doorchime Interface Module connects to the Doorbox Controller that comes with your Doorbell Fon system and will provide a 800ms momentary dry contact closure.