How to Access the Secret Circuit to Existing Home Phone Lines

By John Vivian
Published on December 1, 1995
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It will all work if ... you remember to keep each color wire's polarity and its connections consistent throughout. 
It will all work if ... you remember to keep each color wire's polarity and its connections consistent throughout. 
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1. Hi-lines; 2. Dropline: A & B; 3. Network interface; 4. House entry; 6 Lines: R, G - Phone and B, Y - Open.
1. Hi-lines; 2. Dropline: A & B; 3. Network interface; 4. House entry; 6 Lines: R, G - Phone and B, Y - Open.
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1. Incoming station wire; 2. Wiring block; 3. Extension phone line; 4. Modular wall jack (only R G wires are functional); 5. R J - 11 modular plug; 6. Primary phone cord; 7. Hardwire to accessory (attach to Y B terminals for secret circuit.)  
1. Incoming station wire; 2. Wiring block; 3. Extension phone line; 4. Modular wall jack (only R G wires are functional); 5. R J - 11 modular plug; 6. Primary phone cord; 7. Hardwire to accessory (attach to Y B terminals for secret circuit.)  
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Connecting an R J -11 jack to a coaxial plug.
Connecting an R J -11 jack to a coaxial plug.

Connect to your home phone wiring to pipe music, rig an intercom, or connect electronic devices to existing phone lines. (See the phone wiring diagrams in the image gallery.)

How to Access the Secret Circuit to Existing Home Phone Lines

As long as a half-century ago MaBell anticipated today’s Information Age, and when she self-destructed into seven regional “Baby Bells” in the early ’80s, she bequeathed you house wiring that can handle at least twice as much electronic information as you’d expect it to.

Today’s digital phone transmission systems have confused things with their satellites, microwaves, and optical fibers that can handle a thousand phone calls at once. But back in the analog Dark Ages (a little more than a decade ago), all phone messages traveled from caller to caller–around the globe and back if need be–over a parallel pair of copper wires. Inside your home and throughout most rural and small-town phone systems, they still do.

The signal travels from the telephone pole hi-lines to your home via a heavy, weatherproof, guyed cable called a “drop line.” Inside the cable are two wires, termed Lines A and B (or four wires the added pair called C and D-if you have two separate numbers), which lead down the house wall to a small grey box called the “network interface.” Inside, the phone lines are stripped to bare copper and bound to brass wiring posts. There, they connect to your permanent, fixed house wiring, called station wire. This is a miniature cable-a sheath of white or grey plastic insulation holding four top-quality, 24- gauge, well insulated, solid copper wires.

But, most home phone systems use only two of the four wires–normally the green and red pair. Unless you have two different phone numbers or an especially wired feature-phone network, the black and yellow wires are unused–just languishing inside the station wire that’s tacked with special little U-shaped staples around your baseboards and over the door frames to all your phone locations past and present–and perhaps out to a barn phone–thanks to MaBell’s foresight.

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