Hardening outside phone line for alarm system

[Robert Bass]

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.

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.

[P.J. Hartman]

I would suggest leaving the existing wiring exposed.

Add a conduit from box to house to carry the real, "live" phone wires. A burglar may be smart enough to cut the phone line first, but it won't be the actual phone line.

[JerryMouse]

If the line's cut, how's it gonna call?

[Bill Unruh]

]I would suggest leaving the existing wiring exposed.

]Add a conduit from box to house to carry the real, "live" phone wires. ] A burglar may be smart enough to cut the phone line first, but it ]won't be the actual phone line.

Around here the "box" is high up on a "telphone pole" (well it carries hydro-- electricity to those south of the border-- as well). Ie, there is no ground level box. You have to run the phone line either down the telephone pole, which is the telephone company's property and they really do not like you fooling with it-- or down the house.

[Bill Unruh]

]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.

Except that now they can actually use that copper pair for far far higher data transmission rates-- eg ADSL modems, etc. Thus one could imagine putting an ADSL type signal on the line to the phone company-- or if the user uses ADSL via the user's ISP-- and monitoring that for disruption.

Most homes have two lines (ie two sets of twisted pair) coming in anyway

[alarman]

Bill Unruh wrote

Where do you live, Hooterville?? js

[G. Morgan]

On Tue, 16 Nov 2004 19:31:24 -0800 "alarman" used 12 lines of text to write in newsgroup: alt.security.alarms

I'm trying to figure out how Mexicans use water "hydro" for electricity.

[Robert Bass]

Quite right. As more people start using ADSL and even SDSL, perhaps the alarm industry will begin to take advantage of its capabilities.

[Mark Leuck]

It's called a "dam"

[Frank Olson]

Damn. That's funny.

[Jeffrey J. Kosowsky]

Not sure what part of the above you are referring to, but in much of the Northeast telephone wires come in on "telephone poles" and the wire goes aerially to the drop on the side of the house...

[R.H.Campbell]

Up here in Canada, we refer to "hydro" as the electrical plant

ie: "How much was our hydro bill this month...."

.......or...........

"where does the hydro come in the house...."

And our power supplier is called Ottawa Hydro

RHC

[G. Morgan]

On Wed, 17 Nov 2004 10:46:04 -0500 "R.H.Campbell" used 32 lines of text to write in newsgroup: alt.security.alarms

So what do you call water, electricity?

Hydro and electricity don't mix.....

[jackcsg]

How do they get the water in those little wires? What do yous guys call that blue water in the crapper? Besides a good acid trip.... LOL

Jack

[R.H.Campbell]

Damn ! For once I don't have a good come back....:)))...good one guy....:)))

RHC

[Mark Leuck]

Keep digging that hole deeper.....

[jackcsg]

I'm even laughing to hard to rub it in....flush

Jack

[MC]

co-worker got woke a week ago by his neibor, someone had cut the neibors phoneline an attempted to break in to a window. The husband was away on business, I guess they may have though both were gone. Luckly she had a cell phone and called 911 when she heard a noise outside.

[alarman]

Jeffrey J. Kosowsky wrote

I had this image of you climbing up the pole with a butt set to make phone calls a la Green Acres. js

[davefr]

That's easy. Disguise your NID by relocating it or burrying it in a dry spot. Now setup a dummy NID with a very obvious phone line wire going to it. Wire that dummy phone line to a zone on your alarm.

Burglar cuts what he thinks is a phone line and the alarm goes off. Cheaper than radio or cellphone backup.

(An alternative is to wire the dummy phone line to 220V so the burglar gets dead if he cuts it. Just make sure it's not a lineman for the phone company.)