This system from CHAMBERLAIn is a two part system, consisting of the outdoor doorbell and the inside intercom. When a visitor presses the button on the doorbell it chimes at the intercom and allows a two-way conversation.
1,000 feet of range
Wireless Intercom and Chime
Expandable allowing you to connect multiple rooms
No Wires or Power connection necessary
Battery Operated, AA (4 ea.) for the Doorbell and Intercom
Size: Doorbell - 6.5" x 3.5" x 1.5" Intercom - 6" x 3.5" x 1.75"