Extension Modules – GBX20 Product Description GBX20 4.3 inch (272×480) color LCD 20 per page (each module contains 2 pages, for up to 40 lines per module) Connect 4 modules for up to 160 contacts/extensions See also different: Business Conferencing – GAC2570 GXP Series IP Phones – GXP2160 GXP Series IP Phones – GXP2140 Unified Communications – GRP2603(P)