CENTRAL STATION (CS) SECURITY MONITORING SYSTEMS USE MULTIPLEX TELEPHONE TRANSMISSION TO MONITOR ELECTRICAL PROTECTION CIRCUITS AND DEVICES INSTALLED IN PLANTS, BUSINESSES, OR HOMES. THE CENTRAL MONITORING STATION HAS PERSONNEL ON DUTY AROUND THE CLOCK TO RELAY EMERGENCY MESSAGES TO THE APPROPRIATE ORGANIZATIONS. SINCE THE CS FACILITY IS USUALLY COMPUTERIZED, IT NOT ONLY NOTIFIES THE POLICE OR FIRE DEPARTMENT RAPIDLY, IT ALSO PROVIDES A PRINTED RECORD OF THE TIME OF THE ALARM. MOST CS AGENCIES HAVE DIRECT TELEPHONE TIE-LINES OR PRIVATE SIGNAL CHANNELS TO THE POLICE AND FIRE DEPARTMENTS IN THEIR SERVICE AREAS (WHICH GENERALLY RANGE FROM 30 TO 60 MILES). THE UNDERWRITERS LABORATORIES REGULATIONS GOVERNING THE INSTALLATION OF THE ELECTRONIC DEVICES AND COMMUNICATIONS LINES ARE BRIEFLY REVIEWED. MANY CS AGENCIES OFFER ENERGY MONITORING SERVICES, AND THE ECONOMICS OF SCALE OFFERED BY A CS ARE REVIEWED. THE MAJOR ADVANTAGES OVER A PROPRIETARY ALARM SYSTEM ARE THE PROVISION OF TRAINED PERSONNEL ON A 24-HOUR BASIS, THE AVAILABILITY OF SKILLED MAINTENANCE PERSONNEL 24 HOURS, 7 DAYS A WEEK, INSTALLATION EXPERTISE, LARGER INSURANCE PREMIUM DISCOUNTS, AND THE QUALITY CONTROL POSSIBLE. SINCE IT IS THE AIM OF A CS SERVICE TO AVOID FALSE ALARMS, FAILURES IN EQUIPMENT AND FALSE ALARM DATA ARE MONITORED MUCH MORE CLOSELY THAN IN A PRIVATE SECURITY SYSTEM. THE DIGITAL COMMUNICATOR DOES NOT PROVIDE THE RELIABILITY OF THE LEASED TELEPHONE LINES, BUT IT IS LESS EXPENSIVE, ENABLING SMALLER BUSINESSES AND HOMES TO AFFORD ELECTRONIC SECURITY. THE FUTURE OF CS SERVICES IS SEEN AS EXPANDING. (GLR)