The GBX20 is an Extension Module that adds functionality versatility and flexibility to Grandstream�s GRP2615 Carrier-Grade IP Phone and GXV3350 IP Video Phone. It features a 272x480 LCD display that offers up to 40 contacts per module with support for up to 160 contacts by using 4 modules. The GBX20 supports a wide-range of advanced call features including BLF call park/pick-up speed-dial presence intercom voice conferencing transfer/forward and much more. An ideal solution for businesses and receptionists managing high call volumes the GBX20 ensures maximum productivity by efficiently monitoring and dispatching incoming calls.