Features: 8 feature keys with LEDs Open listening 2 keys (plus, minus) for settings ringer volume, ringer pitch and alerting tone Suitable for wall-mounting Colors: arctic, manganese The Siemens systemphones optiPoint 500 can be connected to the following pbx systems: HiPath 500 Hicom 150 E / 150 H Office HiPath AllServe HiPath 1220 HiPath 3000 Hicom 300 E/300 H HiPath 4000