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. It features a large graphic LCD. 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.