Abstract: An operator interface device is connected to the central control unit of a remotely-monitored security system, which also includes one or more local control units located at monitored sites. A local control unit may initiate a telephone call to the central control unit to alert the operator of an event such as an intrusion at the site. The interface device has a keypad on which the operator can enter commands that are transmitted to the local control unit. A processor in the interface device uses a look-up table, state machine or other predetermined relationship to translate the command entered by the operator into the native or local command recognized by the local control unit.