The Yealink EXP40 Expansion Module is for all compatible SIP-T4x Yealink phones (check product compatibility on phone page).
Yealink EXP40 IP Phone Expansion Module Key Features
160x320 graphic LCD with 16-level grayscales
LCD Backlight
20 physical keys each with a dual-colour LED
Wall mountable
Supports up to 6 modules daisy-chain
The EXP40 expands the functional capability of your SIP phone to a whole new level. Featuring a large graphic LCD, the EXP40 comes with two pages of 20 flexible buttons that are shown on the display. These can be programmed up to 40 various features, the productivity-enhancing features include BLF/BLA, speed dialing, call forward, transfer, park, pickup, etc.