Easy Customization and High ExpansibilityThe SIP-T48U has a seven-inch, 800 x 480-pixel, backlit- color touch screen, which enables a richvisual presentation and easy navigation. Accompanied by two USB ports, the T48U is yourright-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 tovarious features, but also can connect up to three expansion modules, for up to 180 additionalbuttons with a screen-based LCD display and LED system.HD AudioYealink Optima HD Voice technology combines cutting-edge hardware and software withwideband technology for maximum acoustic performance. Being a totally open, highly versatileaudio codec, Opus, is designed to perform a higher HD audio quality than other wideband codecsin a high network bandwidth; However, if your current network quality is poor, Opus can provideyou 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 ProvisioningYealink T4U series supports efficient provisioning and effortless mass deployment with Yealink’sRedirection and Provisioning Service (RPS) and Boot mechanism to help you realize the Zero TouchProvisioning 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 appliesto all T4U phone models (T41U, T43U, T46U and T48U), saves even more time and costs forbusinesses, as well as simplifies the management and maintenance.Secure Transport and InteroperabilityThe SIP-T48U uses SIP over Transport Layer Security (TLS/SSL), which is the latest network securitytechnology. It’s also compatible with leading soft switch suppliers, such as 3CX, BroadsoftBroadworks.