HIR Issue 7: Making a 2 phone line adapter
by Frogman
Ah, the added wonderment of a second line. Fax machine, data line, Dual modems, three way conference on each line, five people at once.. <g> But wait, how am I going to install all this stuff? I've got a student budget for home improvement of 0 dollars and 0 cents. I also have no flexibility to rewire the phone jacks all the way through the house to get two separate lines. I have to use a double line cord with equipment that recognizes only line one.
I solved my little dilemma by remembering that I can just cut the cord and swap wires. This a technical kludge and is not all that elegant. I started sifting through the piles of obscure equipment I keep on hand for just these types of situations.
Axon has seen some of my wierd junk in the Frog lair:
An ancient amber monochrome text display, great for use as a dumb terminal. An original Amiga 1000 system, complete with an IBM emulator Sidecar box. Piles of obscure connectors, like several DB-23's, large DIN8's, DIN6's... Old, old, old palmtop -- Panasonic's Hand Held Computer (HHC) circa 1983. A couple almost useless MFM/RLL/ESDI drives.
A souped IBM PC-XT -- 286 accell, card slots filled out the wazoo...
And a lot of phone junk.
And in my various and sundry phone junk pile, I had nothing that simply split a four wire line into a pair of single lines. I resigned to the fate of skipping the Radio Shack box for $7 and decided to hack a box of my own from spare parts.
I keep several of those breakout boxes that turn one RJ jack into two around, they are invaluable. I found out how much more when I popped one open and looked inside. They are built with wires running from the input side to both outputs. These magic wires are nicely color coded like a standard phone cable! The first thing you should check is that there are eight wires in there. Yes eight, two wires for each line, two pairs for each of the two jacks. If you only have four, then you are outta luck. The only other problem is that sometimes they get the colors for each line backwards, but that doesn't really matter, as long as the pairs match up.
To do my hack, I had to figure out how to get those wires out, swap them around, and get the whole thing back together in the nice beige unit. This means no cutting and soldering/taping the wires. If you look at how your box is built you will see the ways it is held together. On the sides of the box are four square holes, through which you push a pen or paper clip to release the prongs that hold the unit together. Once the two parts release, the only things holding them together are the wires. Where they meet the two jacks, there are some nice, removable inserts that hold the wires in the proper order and position. To get these inserts out, the makers, understanding phreaker needs, provided slots on the front, under each jack, that if you slide a screw driver or a paper clip in they come right out. For this hack, just take out one insert. Unbend the wires, pull them out of the holes, noting what went where, and swap colors. Swap red for black, and green for yellow. Bend the wires back, and replace the insert. Snap the box together, and you are almost done. You must remember to label which side has line one, and which side has line two.
See, it's that easy! You start out with a $2-$3 box, and hack it in five minutes into a $7 box! Now, just plug it into the wall recpticle. Decide what you want for line one use, and jack it up. Do the same for line two. The magic of this approach is that it is completely reversable, will not get accidentally torn apart (in most calm, non-moshpit type homes), and is easily removed and taken with you when you move, unlike rewiring the entire place.
