6873i VoIP SIP telephone, 2 x Gigabit Ethernet, 2 x line keys, 48 x programmable keys (4 pages of 12 keys), PoE required, AC optional, 7 inch touch colour backlit LCD, HD audio, Bluetooth 4.0 support, USB 2.0 port, support for up to 3 x expansion modules (sidecar / attendant console),