Now add up to 4 This versatile digital intercom with keypad system is ideal for any residential application, alerting you of visitors and allowing gate opener activation from the safety of your home. It can be programmed to use up to 25 different personal identification number (PIN) codes. The intercom provides superior range with crystal clear two-way wireless communication up to 500 feet wireless. (Kit includes one base station with rechargeable battery). ** Only operates with "Wireless" Applications.