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, 

nd 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