... receiver sensitivity: less than -100.Product Name: Wireless Voice/Non-visual Doorbell 1,2.4G ISM ... )4,AFH Adaptive Frequency Hopping technology, with wireless LAN and Bluetooth devices share 2.4G band ... Communication distance: 500 meters for barrier free Details:Wireless intercom doorbell is a set of multi-way ... every four seconds3,CALLA:First press the ID number, then the CALL button, enter the main ...