Panasonic 24 Button 6-Line Backlit LCD Display Digital Proprietary Telephone with Full Duplex Speaker Phone, Black KX-DT546-B 24 programmable function keys 6-line Graphical LCD with backlighting Speaker Phone, handset and headset with full duplex EHS (Electronic Hook Switch) Compatible with: Panasonic KX-TDA 50 / 50G / 100 / 200 / 600, Panasonic KX-TDE 100 / 200 / 600, Panasonic KX-NCP 500 / 1000, Panasonic KX-NS1000 phone systems.