Intertel Axxess 550.8500 Basic Digital Phone (Charcoal/Refurbished)The Inter tel 550. 8500 IP Endpoint telephone features 21 programmable keys with lamps, adjustable base, message lamp in right hand corner of unit, and headset jack. Key Features: Red and green lamps indicate when a call is active, ringing or holding Self test function to check all keys, lamps and LCD Compatibility: Works with the Inter Tel Axxess System