United Yealink Optima HD Voice technology, the T44U awards you superb audio quality and crystal-clear voice communications. The phone feels quicker and more responsive when performing call features. The T44U 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 Yealink new T4U series offers the same elegant appearance as the T4 line, but with improvements for greater interoperability and better collaboration. The T4U series better builds the Yealink ecosystem and is compatible with more Yealink headsets, supporting intelligent channel switching* and using the phone to configure and upgrade headsets.