Yealink SIP-T53 12 Line IP HD Phone, 3.7" Display, 360x160 LCD Screen with Backlight, Supports up to 12 VoIP Accounts, Dual-Port Gigabit Ethernet, HAC Handset, Wall Mountable, Supports 3-Way Conferencing, 01 Year Limited Warranty The Yealink SIP-T53 is a 12-Line Gigabit IP Phone that features wideband HD Voice audio and full-duplex speakerphone with echo cancellation. It has a large backlit monochrome display that clearly shows letters for easy reading. The screen is adjustable, so you can position it for your height. The SIP-T53 supports 12 lines, as well as 3-way audio conferencing.