Polycom 650 SoundPoint IP Backlit Expansion Module large, backlit grayscale LCD with multiple functions and a user-friendly call visualization Hot swappable, easy plug-and-play setup, host phone provides power and signaling Fourteen illuminated keys configurable as a line appearance or a speed dial with busy lamp The ability to add up to three modules to a single host phone, adds fourteen lines per module Intended to be used with the Polycom Soundpoint IP 650 Phone