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 a 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 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 efficiency and productivity