Yealink optima hd voice dual port gigabit ethernet codecs: opus, g. 722, g. 711 (a/ų), g. 723. 1, g. 729ab, g. 726, ilbc display: 2. 7" 192x64 pixel graphical lcd with backlight up to 12 sip accounts 6 line keys with dual color leds can be programmed with up to 15 features (3 page view) 4 soft keys paper label-free design one rj9 headset port with ehs support (with ehs36 wireless headset adapter) integrated stand with 2 adjustable angles wall mountable with wmb-t4s kit poe 802. 3af, class 2 no power supply included (ps5v1200us) upgrades from t42g device performance enhancement with fastr response on the phone's user interface opus support enhanced speaker performance usb port for bluetooth headset with bt40 dongle or wifi support with wf40 dongle united firmware hearingpatible handset