Easy Customization and High Expansibility The SIP-T48U has a seven-inch, 800 x 480-pixel, backlit- colour touch screen, which enables a rich visual presentation and easy navigation. Accompanied by two USB ports, the T48U is your right-hand man in the office that makes Bluetooth, Wi-Fi, USB headset and USB recording possible, and you can use any two of them freely according to your needs to enrich phone features. Meanwhile, the phone not only has 29 one-touch DSS keys that can be easily programmed to various features, but also can connect up to three expansion modules, for up to 180 additional buttons with a screen-based LCD display and LED system. HD Audio Yealink Optima HD Voice technology combines cutting-edge hardware and software with wideband technology for maximum acoustic performance. Being a totally open, highly versatile audio codec, Opus, is designed to perform a higher HD audio quality than other wideband codecs in a high network bandwidth; However, if your current network quality is poor, Opus can provide you with a better audio quality than other narrowband codecs. And its hearing aid compatible (HAC) handset helps the person who is with hearing loss to hear the voice more clearly. Efficient Installation and Provisioning Yealink T4U series supports efficient provisioning and effortless mass deployment with Yealink – s Redirection and Provisioning Service (RPS) and Boot mechanism to help you realize the Zero Touch Provisioning without any complex manual settings, which makes the T4U series simple to deploy, easy to maintain and upgrade. Furthermore, a unified firmware and auto-p template that applies to all T4U phone models (T41U, T43U, T46U and T48U), saves even more time and costs for businesses, as well as simplifies the management and maintenance. Secure Transport and Interoperability The SIP-T48U uses SIP over Transport Layer Security (TLS/SSL), which is the latest network security technology. it is also compatible with leading soft switch suppliers, such as 3CX, Broadsoft Broadworks.