A security system including a main control unit, a plurality of sensors and a user interface device. The main control unit communicates with a remote central monitoring station when a sensor detects an alarm event. Once the communication signal from the main control unit is successfully transmitted to the central station, a siren is sounded. Thus, the delay time to trigger the siren is dynamic based on the time it takes for successful transmission of an alarm notification to the central station. This dynamic delay accounts for transmission interruptions between the security system and the central station and allows the location of the main unit and/or the siren from being detected prior to successful alarm transmission to the central station.