Additional Details ------------------------------ Product description: Especially designed for busy executives and professionals, Yealink SIP-T53 is an easy-to-use Prime Business Phone with an adjustable 3.7-inch graphical LCD that you can easily and flexibly find the comfortable viewing angle according to the personal and environmental needs. Working with Yealink Bluetooth USB Dongle BT40 and Yealink Wi-Fi USB Dongle WF40/WF50, the SIP-T53 IP Phone ensures you to keep up with the modern wireless technology and take the first chance in the future wireless age. Its built-in USB 2.0 port allows for USB recording or a direct wired/wireless USB headset or up to three Yealink EXP50 expansion modules connection. Benefitting from these features, the Yealink SIP-T53 is a powerful and expandable office phone that delivers optimum desktop efficient and productivity.