Since the DoorKing telephone intercom system uses the existing telephone line and the residents telephone for communication, any telephone in the house can be answered to establish communication, and open the door or gate.

DoorKing's 1812 has built-in call waiting, allowing the resident to place an outside call on hold while they speak to the visitor, and then switch back to their call. A call forwarding function even allows calls to be sent to another telephone automatically if the resident is going to be away from home. Plus, up to three additional outside phone numbers can be programmed allowing visitors the means to contact other phones on the property!

DoorKing's 1812 includes a built-in time clock allowing the resident to program many time related features like Do Not Disturb times and automatic Call Forwarding times. In addition, the resident can schedule times for the door or gate to open and close automatically without the need of an external time clock, and can time zone restrict certain entry codes. DoorKing's unique "Flash" code feature lets the resident program a four digit entry code that works on a specified day only - then turns itself off! In addition to these great features, the 1812 is designed with a built-in stand-by power source that will maintain the current time and date, and all time related programming functions, should a power outage occur.