Someone always seems to come to the door at the most inconvenient time. But you don't need to install an expensive intercom system in order to find out who's ringing the bell. The Doorbell Fon Door Answering System connects your doorbell to your telephone, so you'll be able to pick up any extension in the house to talk to your visitor. When a visitor presses the non-mechanical sensor button on the included aluminum door box, the telephones will ring with a distinctive ring to let you know someone is at the door. Pick up any telephone to be connected with that door automatically. If you are on the phone, you'll hear a call waiting tone; switch over to the other line to talk to your visitor. The Doorbell Fon control unit requires connection to only one incoming line and one door station (included). A second door station may be added to the controller to operate another entryway. You won't lose a phone jack by installing the controller: Connect your incoming line to the controller, and connect your phone into the controller's "line out" jack. By installing modular add-ons, you'll be able to add even more functionality to this doorbell answering system. The Inbound Relay Trigger Controller provides momentary contact closure from the push button on the door box. This can be used to trigger a door chime, lights, or even a camera for added security or alert signals. The trigger controller as well as any door chimes, lights or cameras are sold separately. An Outbound Relay Trigger Controller provides dry contact closure off the star key (*) on your telephone to operate an electrical device, such as a door release, to allow entry to your visitor without your having to leave your couch. This is especially handy when used on electric gates at the end of the driveway or property. The Doorbell Fon Door Answering System can be connected to a regular house phone as well as to a two-line or PBX system. The Doorbell Fon Door Answering System is also available in Ivory, White, and Brass. Turn every phone into your house into an interior intercom with the Doorbell Fon Intercom Module (sold separately). Protect your Doorbell Fon unit from the elements by installing a single-gang or double-gang awning over the exterior component.