PoE Class 2 Swivel graphic display, 3.7" (240*120 pixels), monochrome LED backlight (white) Signaling LED (red/green/yellow) 4 context sensitive soft keys with LED (red/green/yellow) 2 fixed function keys (Menu/Out-of-office) 16 freely programmable function keys with LED (red/green/yellow) 4-way navigator, plus OK button 3 audio function keys (mute/loudspeaker/headset) with LED volume +/- open listening / hands-free (Full duplex) Headset interface (DHSG/EHS) 10/100/1000 Base-T Ethernet Switch IEEE 802.3az Energy Efficient Ethernet IEEE 802.3af Power over Ethernet, Class 2 Key Module 400 optional (max. 2)