The audio door telephone controller device is connected to the telephone extension at the door. When the door needs to be opened, the visitor dials the telephone in the room on the door operator. After confirming the identity of the visitor through the telephone, the internal staff can enter the password on the telephone to open the door remotely.

The audio door telephone system is mainly composed of host, extension, UPS power supply, electric control lock and door closer. According to the type, it can be divided into direct press type, digital type, digital household communication, direct press type visual intercom, digital visual intercom, digital household communication visual intercom, etc.