The EXP40 Expansion Module is designed to enhance the flexibility and call-handling capacity of the SIP-T46S, SIP-T46G, SIPT48S and SIP-T48G IP Phone. It features a backlit 160×320 Graphic LCD and provides two pages of 20 flexible buttons, paired with a dual-color LED.
Manufacturer Link:
https://www.alloy.com.au/products/EXP40/