X3U VoIP SIP telephone, 2 x Gigabit Ethernet, 3 x line keys, PoE required, AC optional (SKU #PS5V1A), 2.8 inch colour LCD, HD audio, RJ9 headset jack, EHS support for specific Plantronics headsets (CS 500 series, Savi 700 series, Voyager Legend CS, SKU's required #PLGEHS80 and SKU #PL8563801) and specific Jabra headsets (Jabra Pro 920 / 925 series, SKU required #FNEHS20).