This intercom system uses GSM phone technology to call the property at which it is installed. The visitor presses the call button to initiate the call to a designated phone which may be a land line or mobile. Once the call is answered, two way conversation is possible. The door or gates can also be opened by the called phone. Up to 250 phones stored in a white list can open the gates or door by simply calling the telephone number of the 4K intercom. This system can expand up to 50 call buttons.