A Revolutionary SIP Phone with

a 7-inch Touch Screen 

The SIP-T48U IP Phone 

CSS presents a dynamic business communication solution to executives and professionals with the new SIP-T48U IP phone. The phone employs an appealing large touch screen that makes the switch between pages and applications swift, easy and convenient. United CSS Optima HD Voice technology and wideband codec of Opus, the T48U awards you superb audio quality and crystal-clear voice communications. Moreover, the T48U puts dual USB ports in a phone that makes Bluetooth, Wi-Fi, USB headset, and USB recording come true, and you can use any two of them freely according to your needs. The new CSS T4U series offers the same elegant appearance as the T4 line but with improvements for greater interoperability and better collaboration. 

Easy Customization and High Expandability 

The SIP-T48U has a seven-inch, 800 x 480-pixel, backlit-color 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 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 and LED system. 

HD Audio 

CSS Optima HD Voice technology combines cutting-edge hardware and software with wideband technology for maximum acoustic performance. Being an 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 network quality could be better, Opus can provide better audio quality than different narrowband codecs. Its hearing aid compatible (HAC) handset helps the person with hearing loss hear the voice more clearly. 

Efficient Installation and Provisioning 

CSS T4U series supports efficient provisioning and effortless mass deployment with CSS’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 T42U (pending)/T43U/ T46U/T48U phone models saves even more time and costs for businesses, as well as simplifies the management and maintenance. 

Secure Transport and Interoperability 

CSS T4U series uses SIP over Transport Layer Security (TLS/SSL), the latest network security technology. It’s also compatible with leading soft switch suppliers, such as 3CX and Broadsoft Broadworks. Moreover, it is carried with dual firmware images that give you enterprise-level protection to avoid bricking your system once the upgrade fails.


  • 7” 800 x 480-pixel color touchscreen with backlight
  • Opus codec support
  • Dual USB ports
  • Dual firmware images
  • T42U (pending)/T43U/T46U/ T48U Auto-P template unified
  • T42U (pending)/T43U/T46U/ T48U firmware unified
  • Up to 16 SIP accounts
  • Dual-port Gigabit Ethernet
  • PoE support
  • Paperless label design
  • Headset, EHS support
  • Wi-Fi via WF40/WF50
  • Bluetooth via BT40/BT41
  • USB recording
  • Supports colour-screen expansion modules
  • Stand with two adjustable angles
  • Wall mountable


  • SIP-T48U IP Phone Data Sheet