Best Alarms Are Great Communicators

There are only a few basic kinds of home security alarm systems.

All other things being equal--such as the sophistication of internal sensors, the activation of local alarms and how they communicate within a house--what separates them is whether and how they communicate distress to the outside world.

Today’s most high-tech systems, called digital communicators, use the phone to alert a central monitoring station about a breach in security. This agency then notifies the appropriate emergency service.

Initial communication between the home system and the agency is automatic and voiceless.

These digital communicators send a burst of coded information to the central station, which then uses the open line to make voice contact with the home or otherwise assess the situation. This includes monitoring the sensors within the home--live and on-line. Meanwhile, the central agency is in voice contact with local authorities, who will dispatch assistance as needed.

The critical elements here are the system’s ability to communicate beyond the home, automatically, and the monitoring agency’s person-to-person contact with the emergency services.

Systems that only activate internal or external sound and light alarms depend on being heard--and heeded--then on someone alerting the police or fire department.

Screaming sirens and flashing strobes within a house might succeed in dissuading an intruder. Externally audible and visible signals might cause a neighbor to raise an eyebrow and the telephone.

But with systems that don’t call for outside help, there’s no guarantee that the cavalry will come.

Some non-digital home security devices do have the ability to make calls automatically to designated numbers that are stored in memory. Unlike digital communicators, these simply play a voice message that you’ve previously recorded.

Although you might hire a 24-hour monitoring agency to be on the receiving end, usually these voice-message devices are marketed as a less-expensive alternative to monitoring services.

You can program the auto-dialer to make direct calls to a neighbor or perhaps another phone where you can be reached. The other party can listen in on the open line after hearing your message, but there’s no digital reporting of system status or remote electronic monitoring of the situation.

If you have this type of system, do not program it to directly call police or fire departments.

During an earthquake or other major disaster, this type of alarm will completely block incoming phone lines at police and fire stations.

If you’re not home when the alarm sounds off, there’s no way to confirm or cancel the call. These systems usually cost $100 to $200, depending on packaged sensors and accessories. The most widely available of these is the Voice Dialer Console in the PowerHouse line from home automation giant X-10 USA. The same item comes in several brands, including Radio Shack’s Plug’n Power line.

Police officials say any alarm system should include a fail-safe battery backup, fire-sensing capability (ionization sensors are best), readout ability to check the working of the system and a horn-sounding device.

Before installing any alarm system, consult your local law enforcement agency. Get several estimates before deciding which alarm company and system is best for your needs.

A system that phones out probably is better than a siren that falls on deaf ears, but one that isn’t centrally monitored might create a sense of false security--and false alarms.