newman@uunet.uu.net (Bo Newman) (10/03/89)
I am trying to help a friend install an auto dialier on his home
security system and I need some information on "line capture
units". I understand that the one you can get from the "phone"
company is called an RJ31X. My questions are:
1) Where is it installed? (a) In series between the point where
the phone line enters the house and all other phones? (b) on
the local loop but not at the house? or (c) elsewhere.
2) What alternatives exist?
3) How does it work?
4) Are there any restriction on the distance between the RJ31X
and the "Controling Device"?
An addition question related to this instalattion, is anyone aware
of the need for special permits to operate an alarm auto dialer in
Maryland 301-551-xxxx.
Please Respond via E-Mail ... If there are enough responses, I'll
post a summary.
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:Bo Newman newman@inco.uu.net uunet!inco!newman :
:McDonnell Douglas Electronics Systems Company (MDESC-WDC) :
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===================================================================johnl@esegue.segue.boston.ma.us (John R. Levine) (10/04/89)
An RJ-31 is a specially wired connector placed in series with the
phone line near where it enters the house, in front of all the other
phones. You plug an 8-position miniature phone plug into it. Four
wires are used: pins 5 and 4 are tip and ring from the phone company,
and pins 8 and 1 are tip and ring to the rest of the phones. The
equipment you plug in, most often a burglar alarm, normally bridges 1
to 4 and 5 to 8, so the rest of the phones act normally. When it
wants to make a call it can butt in, force a hangup, and do whatever
it wants.
There are little shorting bars in the RJ31 socket that bridge 1 to 4
and 5 to 8, so if you unplug the equipment the rest of your phones
work.
The best place for the RJ31 is inside the alarm control box where a
burglar can't unplug it easily, but they usually seem to be installed
near where the phone line enters the house.
Regards,
John R. Levine, Segue Software, POB 349, Cambridge MA 02238, +1 617 492 3869
johnl@esegue.segue.boston.ma.us, {ima|lotus}!esegue!johnl, Levine@YALE.edu
Massachusetts has 64 licensed drivers who are over 100 years old. -The Globejeh%sdcsvax@ucsd.edu (10/10/89)
In article <telecom-v09i0431m07@vector.dallas.tx.us>, johnl@esegue.segue.boston.ma.us (John R. Levine) writes: > An RJ-31 is a specially wired connector placed in series with the > phone line near where it enters the house, in front of all the other > phones... (nice description of RJ-31 elided) > The best place for the RJ31 is inside the alarm control box where a > burglar can't unplug it easily, but they usually seem to be installed > near where the phone line enters the house. This reminds me of a place I used to work which had an autodialing burglar alarm. The alarm was triggered by opening any of several protected doors from the public corridor into the private office space, with a 30-sec or so delay. Authorized personnel were supposed to come in through one particular door, near which was the keypad which would let you cancel the alarm before it called the alarm company. The alarm control box was installed right next to the keypad. An intruder would have no doubt as to what the box was because when the timeout expired the box could be heard pulse-dialing with a relay (click-click-click... click-click-click-click-click... etc.). The sound was unmistakeably that of a telephone dialer at work. Of course the box was locked. But, leading out from the box and stapled to the wall in plain view was the standard beige-jacketed 4-conductor inside phone wire! Obviously if one didn't want to take time forcing the lock on the control box, a simple snip of the phone wire would keep the box from calling anybody! And, since it used pulse dial, there'd be plenty of time to hear the dialing, notice the wire, and cut it... The same place had a lock on the elevators, so that after hours, you had to use a key or the elevators wouldn't stop at their floor. (The stairwell doors were normally locked from the stair side.) The control panel on which the lock was mounted (inside each elevator car) was secured by six ordinary phillips-head screws. The keyswitch was positioned right next to the button for the floor, making its function rather obvious ("Gee! This button doesn't work! I'll bet this lock has something to do with it!"). Unless its backside was protected in some way a simple clip lead across its terminals would suffice to "hot wire" the elevator. No doubt they had paid big bucks for all this stuff, and felt secure... I pointed all this out once, but they didn't want to hear it, to put it mildly. --- Jamie Hanrahan, Simpact Associates, San Diego CA Chair, VMSnet [DECUS uucp] and Internals Working Groups, DECUS VAX Systems SIG Internet: jeh@simpact.com, or if that fails, jeh@crash.cts.com Uucp: ...{crash,scubed,decwrl}!simpact!jeh