Colleague Line Powered CID-BK "Improved Super-Twist LCD Screen: improved viewing and reduced glare,Ratchet-Type LCD Display: allows user to select viewing angle Both 90 Volt and 24 Volt Message Waiting Lamps Headset Jacks (2.5mm and RJ type),Features Include:Line Powered,Caller ID with Call Waiting 60 Message CID Memory,Extra Large 3-line LCD Panel,Voice Message Indication: FSK, 24 Volt and 90 Volt,Speakerphone,Mute with LED,Electronic Hold,11 Direct and 10 Keypad Memories Flash,Redial,High Profile Ring Indicator Multi-Step Volume Control,Data Port DTMF Dialing,Desk/Wall Mountable"