Wireless video door phone

There are many wireless doorbell system, they use kinds of technologies, for example Zigbee, 433Mhz, Bluetooth, 2.4Ghz etc. 

All of these technologies has its advantage and disadvantages. For example, Bluetooth bandwidth is large, but transmit distance is short.  433Mhz transmit distance is long, but its bandwidth is small, can't carry video signal. 

Nowadays, there is a technology can reach long distance and also bandwidth is large enough for video intercom. That is IEEE 802.11ah (WiFi HaLow) our video intercom, 900Mhz frequecy is the best frequency to penetrate the wall， with 5 walls it still can reach 150 meters intercom distance. In the open air, it can reach 1000 meters intercom distance.