Video doorbell as a convenient and practical products, since the late nineties so far, mainly used in commercial 

residential buildings, the rapid development of the scale, has now generally entered the urban residential high-rise 

residential. When used, households hear ringtones, like answering videotapes, accept visitors through 

the downstairs door call, dialogue, while the home of the visual extension can be received through 

the downstairs host camera video images, household observation extension display The screen to monitor 

the image to confirm the identity of the visitors, and finally decide whether to press the indoor extension of

 the button to open the door to connect the door of the electronic control door locks, allowing visitors to open

 the door to enter