As soon as you enter the building now, there is a display screen next to it. What is that for?

This is an access control system, installed at the door of the unit and inside each household. The door to the unit is usually equipped with a security door, and you cannot enter the unit without a key. When there is a visitor, press the number of the visiting room (usually the room number) outside the downstairs security door, and it will be connected to the indoor access control system for a visual call. The indoor personnel can open the downstairs security door by operating the indoor access control system. , to allow visitors to enter.