My understanding is that, if your alarm system is
actually monitored, then cutting the line will
cause the alarm co. to react as if the alarm had
gone off, so hardening it is pointless.

Unfortunately, that is not the case with any but a very few high end systems
for banks and such. Residential alarms are typically monitored using the
switched telephone network. In somple terms, the alarm makes a phone call
to the central monitoring station's alarm receiver. If the line is cut no
call is made and the alarm company does not know it.

Many years ago it was common to build systems with "line security." A
dedicated copper pair was connected from the protected premises, through the
telephone company central office to the alarm central station. A voltage
was applied to the cable. Two different resistors were wired between the
circuit and earth ground. Shorting one resistor meant burglary or holdup.
Shorting the other meant fire. A line cut showed as a trouble condition.

In another ancient system a loop of cable was connected from the alarm
company, through the C.O. and then through an alarm Mc Cullough (I forget
how it was spelled) transmitter at each protected premises. Upon alarm a
motorized cam wheel would close and open a switch, creating a series of
interruptions in current on the loop. At the alarm company office this was
translated into a series of marks or holes in a tape designating the account
number. A clerk then looked up the account called the local authorities.
If the line was cut an alarm company agent would be dispatched to
investigate. The problem is these loops were long and many properties were
often connected to each loop. It could take many hours just to find which
property has a fault.

Another problem with leased line security is most telco's don't want to
provide the dedicated copper pairs any more. They can make far more
profitable use of that single pair as part of the dial-up system. Finally,
new outside plant lines are gradually switching over to fiber optic which
does not support inexpensive line security devices.

Is there some reason why you don't trust the alarm
company to answer these questions?

No offense, but the primary purpose of this newsgroup is to provide a place
where people can share information on alarms. The gentleman's query is
on-topic and appropriate.

--

Regards,
Robert L Bass

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Bass Home Electronics
2291 Pine View Circle
Sarasota · Florida · 34231
877-722-8900 Sales & Tech Support
http://www.bassburglaralarms.com
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