The Chamberlain Wireless Doorbell & Intercom System allows you to speak to family members and guests from anywhere in their home. Featuring a 1,000 foot, 900 MHz range, this system delivers crystal clear digital communication. This system includes one wireless doorbell and one wireless portable intercom. Expandable up to 64 additional units per network, you can enhance a homes communication to multiple locations in a snap. In minutes, you can be completely set up without any wires or power connection required. This convenient communication can be used inside or outside of a home or an office.IELNDIS. NDIS. Chamberlain CHAMBERLAIN NDIS Wireless Doorbell & Intercom System.