Panasonic KX-T7633-B Digital Telephone Black 3-Line LCD Proprietary Phone Requires Panasonic PBXPanasonic 7600 Series Telephone 3 Line LCD Backlit Display. Speaker phone. 24 Programmable Buttons XDP Feature Digital phone can be used with all KX TDA systems. Panasonic KX T7633 B Digital Telephone Black 3 Line LCD Proprietary Phone. Does not work standalone and requires a Panasonic PBX system. Works on all TDA TDE NCP NS systems.