Patent attributes
An entrance intercom system comprises the following elements. A data base is applied to store the resident codes, the phone numbers and the identity recognizing codes of the residents. A communication module is coupled with public switch telephone networks to provide the communicating function between the visitors and the residents, and to receive the incoming phone calls. A CPU responsive to the resident codes input by the visitors can select the phone numbers of the resident stored in the database, and drive the communication module automatically to phone the resident. An incoming phone numbers collecting module is applied to collect the incoming phone numbers. The CPU can compare the incoming phone numbers and the numbers stored in the database. When the incoming phone number is identical to one stored in the data base, the CPU can unlock the gate.
