X4U VoIP SIP telephone, 2 x Gigabit Ethernet, 3 x line keys, PoE required, AC optional (SKU #PS5V2A), 2.8 inch main colour LCD, 2.4 inch side color display for DSS keys, HD audio, RJ9 headset jack, USB, optional Bluetooth USB (SKU #FNBT20) or optional Wi-Fi USB (SKU #FNWF20), 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). Technical note: If the telephone is wall mounted, the USB port is NOT accessible.