Screen : 3.4-in., 384 x 128 backlit pixel monochrome LCD with anti-glare bezel Lines : Single line with a user experience of multiple calls per line Networking : 10/100 Base T Ethernet connections Voice Codecs : G.711a-law and mu-law, wideband (G.722), G.729a, G.729ab, Internet Low Bitrate Codec (iLBC), OPUS Network Features : Session Initiation Protocol (SIP) for signaling, Session Description Protocol (SDP), IPv4, IPv6, User Datagram Protocol (UDP) (used only for Real-Time Transport Protocol [RTP] streams), Dynamic Host Configuration Protocol (DHCP) client or static configuration, Gratuitous Address Resolution Protocol (GARP), Domain Name System (DNS), Trivial File Transfer Protocol (TFTP), Secure Hypertext Transfer Protocol (HTTPS), VLAN, Real-Time Transport Protocol (RTP), Real-Time Control Protocol (RTCP), Cisco Discovery Protocol, LLDP (including LLDP-MED), Switch speed auto-negotiation Signaling protocol support : Session Initiation Protocol (SIP) Power Supply : IEEE 802.3af Power over Ethernet (PoE) Class 2 for low power consumption. An optional external universal AC power supply kit is available. The product is qualified by the Energy Star organization. Dimensions : 226 x 226 x 54.4 mm Weight : 0.907 kg