Yealink T4 series Expansion Module The EXP40 Expansion Module for the SIP-T46S, SIP-T46G, SIP-T48S and SIP-T48G. Expanding the functional capability of your sip phone to a whole new level. Equipped with a 160x320 graphic LCD with Backlight. 20 physical keys each with a dual-color LED and two page views are possible. Supports up to 6 Expansion Modules for an attendant console application, adding up to 240 additional buttons. Two pages of 20 flexible buttons are shown on the display can be programmed up to 40 various features, the productivity-enhancing features include BLF/BLA, speed dialing, call forward, transfer, park, pickup, etc.