The SIP-T43U IP phone is a feature-rich business tool for excellent communications and extended functionality. Integrated with Hall Switch, T43U gives you a quieter operation and environment. It is a 12-line IP phone that comes with a 3.7-inch large black-and-white screen and the EXP43 support. United Yealink Optima HD Voice technology, the T43U awards you the superb audio quality and crystal-clear voice communications.