Security Alarm System dial-out help

[crooter]

I am going to put this note in the cabling forum as well since I think alarm techs might visit that forum.

From time to time I relocate customers dial tone from one provider to another on a new 66 block. When customers have alarm systems they are usually cross connected to one phone number but somehow they are spliced or bridge clipped to reflect an IN and an OUT. Seems like when I try and replicate this, I short out the line (usually shared with the fax or the last number in their hunt group)

Can anyone tell this numbskull how to do this without shorting out the line---I suppose if I know the steps I can keep it from shorting it out, but at this point all I do is keep one side attached to the alarm system.

HELP

 

[ravnz5]

The key is the RJ31X jack for the alarm system. I have installed many of these. You need 2 pairs. Run a cable from the incomming dial tone to the jack and install white/blue pair on pins 4&5 of jack. The white/orange pair goes on pins 7&8. Now at the dialtone incomming location take the white blue pair to the dial tone being used. The white/orange pair should have that dial tone on it at this point. Take that to any or all devices that need that dialtone. When alarm is set off it will grab that line, disconnecting everything else from it so the alarm can dial out. It is very simple if you have the RJ31X jack.

We all need a little help once in awhile. Tony the Phoneman..

 

[crooter]

Thanks Ravns5 but there is not an rj31x in the several situations I have run into. It looks as though the 2 pair cable goes directly to the Alarm box. however---if I follow what you suggested, if dial tone comes in on the white/slate pair of the feed cable, I would cross connect the reg/green to that pair and then cross connect the yellow/black to the station cable going out to the fax line.

or am I off?

 

[donb01]

The RJ31X is sometimes located inside the alarm cabinet to prevent tampering, that is why it looks like the cable runs right into the box - of course if you open the box to look and it has a tamper switch on it you will alert the alarm company at the very least!

You are correct in what you say. The red/green will go to the security system for its use and it will send you back the dialtone on the yellow/black for whatever uses you have for it (fax, modem, phone system, etc).

As explained above, this system is designed so that if an alarm goes off the security system can disconnect any downstream devices from the phone line and basically have the line all to itself - kind of like how a modem will disconnect it's second convenience phone jack when you dial out to prevent you from picking up the phone by accident (and why most newer modems won't work if you plug the cord into the wrong jack on the modem).

Basically an RJ31X jack looks like a regular phone jack except it has an RJ45 (Data-type) plug hole in it. When the RJ45 phone cord from the security system is plugged in the dialtone goes in on pins 4+5 like a regular phone and comes back out on pins 7+8. Theoretically if you unplug the cord from the security system there would be no way for the dialtone on the red/green wires to get back on the yellow/black wires because the security system is not there to pass it along - so inside the jack there is a special shorting bar that connects the two pairs together if you unplug the security system. Also, because the primary dial tone is on the center 2 pins like a normal phone jack, if you plug in a regular phone or a tone generator for testing that device will still work (but the ones on the yellow/black pair would be disconnected when you plug in the standard RJ11 cable).

If you google RJ31X you might be able to find an illustration that explains it better than I did - I have a venfor catalog that I keep around because it has all these jacks illustrated in the back and explains their usage.

 

[crooter]

Thanks DonB01---you did a great job--I understand it now