Nortel Audio Conferencing Units extend voice connectivity to conference rooms and offices with clarity and reliability. It includes full-duplex technology and a keypad to access all of the conferencing features available from your Norstar or Business Communications Manager system. The Norstar Doorphone enables office personnel to talk directly with visitors prior to their entering a business. When a visitor presses the Call Button, the Norstar system rings the designated phone(s) in an office and allows two-way conversation. The optional Door Opening Controller enables any Norstar phone to control a latch on a door or a gate. NRG Communication specializes in the sales and support of popular audio conferencing and door phone units.