The DB200 combination model features a built-in telephone signaler and outlet for connecting a lamp. Just plug the telephone cord into a modular telephone jack (does not draw from phone line power). (Optional extra doorbell button must be purchased for use with intercoms.) Signals all Sonic Alert remote receivers. Features: Selectable number of flashes Flash code for front and rear doors Works with most home intercom systems with a separate additional doorbell button sensor (sold separately) Built-in chime (can be turned off) Works with VP200 and ZBox Doorbell uses a 12V battery (included) What else do I need to make this work? In order to be notified in additional rooms, you will need to purchase a receiver that lets you know when the signaler or transmitter is activated