A. Local Alarm - A bell or light is activated. B. Central Station System - The alarm is transmitted over telephone lines to a central station. The authorities are notified and runner is sent to location. Direct Wire System - a direct dedicated telephone line to central station or police station where a separate receiver supervises only that alarm. Used for high-risk locations such as banks, jewelers and furriers.
Advantages are quick response and difficult for burglars to tamper with.
Disadvantages are high cost of dedicated telephone line and broken lines are not unusual. Alarms are recorded by codes for each establishment. Circuit-loop alarms have the advantage of lower cost. This is the introduction of computer techniques to the alarm industry. The National Crime Prevention Institute has long endorsed alarm systems as the best available crime deterrent.