Yealink optima hd voice codecs: G.722, g.711(a/µ), g.723, g.729ab, g.726, ilbcdual-port gigabit Ethernet 4.3" 480 x 272-pixel color display with backlight built-in a usb port, support Bluetooth headset (through usb dongle) up to 12 sip accounts paper label free design headset, ehs support integrated stand with 2 adjustable angles supports expansion modules wall mountable (optional) simple, flexible and secure provisioning options poe (power over Ethernet) support power supply not included.