All alarm systems consist of the basic elements of detection (ultrasonic, microwave, magnetic switches, and beams), transmission (getting the signal out), annunciation (indication and recording of the signal), and response (reacting to the situation). Unless all four of the elements are carefully analyzed, balanced, and integrated, the security system will be useless. Every cargo or storage facility requires a careful analysis of the most vulnerable areas of attack. The most critical areas are overhead doors used for delivering and shipping, exit doors, outside perimeter walls, interior doors, ceiling, and interior storage areas. Each of these areas must be protected regardless of the number of guards on the premises. New devices called volumetric alarm systems have proven more difficult to compromise than door switches and beams. These systems flood areas with unseen waves that detect movement in the area in three dimensions. The most accepted techniques are ultrasonic, microwave, audio, and passive infrared. During the early 1970's, most detectors used were ultrasonic. When it was demonstrated that microwave detectors are able to protect larger areas than the conventional 30-by-30 feet configuration of most ultrasonic units, they began to capture a good share of the market. More recently, the passive infrared device has made inroads in the market when optics were perfected to allow the unit to change the old-fashioned light beams in distance of coverage. The primary communications transmission systems used today are tape dialers, digital communicators, dedicated/leased direct wire phone lines, McCulloh loop and multiplexing networks, and radio transmission. The customary use of wire to interconnect sensors, control panels, and annunciators provides the most effective transmission technique. The constant threat of the phone company to curtail use of dedicated copper wires for alarm use has led to techniques that permit 'shared' lines.