The GXP2000 Expansion Module (EXT) features 56 fully programmable buttons (each with dual-color LED) when used with GXP2000. The GXP2000EXT is connected to and controlled by the GXP2000 with a short cable included with the module. The GXP Expansion Module supports the traditional call features on each of its programmable buttons, including BLA and BLF. You can daisy-chain 2 EXT Modules to add 112 fully programmable phone extensions to the GXP. The first module is powered by the GXP2000.