The GXP 2200 EXT EXPANSION MODULE module is supported by the GXP 2140, GXP 2170 and GXV 3240. The module includes 20 dual-colored extension keys and 2 arrow keys for page switching (allowing each GXP2200EXT to support up to 40 contacts/extensions.) and features a large backlit LCD screen for easy viewing. Connect up to 4 GXP 2200 EXT EXPANSION MODULE modules to compatible Grandstream phones for a total of 160 contacts/extensions. This expansion module supports traditional call features on each of its programmable buttons, including BLF (busy lamp field, standard or event list)Call Park/Pick-up, Speed Dial, Presence, Intercom, and conference/ transfer/forward. The GXP 2200 EXT EXPANSION MODULE is the ideal solution for users that manage high call volumes, including executives and receptionists. By using the GXP 2200 EXT EXPANSION MODULE the telephone attendant can maximize productivity by efficiently monitoring and dispatching multiple incoming calls.