The Yealink EXP38 Expansion Module has been designed to improve the power and flexibility of advanced Yealink IP phones. It features a 38 fully-programmable DSS key search function, each with a dual-color LED. The module is connected to and controlled by the IP Phone with an RJ-12 cable line. Up to 228 additional programmable extensions are created when six EXP38 units are daisy-chained together with the IP Phone. Yealinks advanced IP phones also have IP-PBX support functions, such as speed dialling, and BLF/BLA, intercom, call forward/transfer/hold/park/pickup/return via programmable EXP38 buttons. The Yealink EXP38 is ideal for receptionists, administrative assistants, call-center agents, power-users and executives who need to monitor and manage a large volume of calls on a regular basis.