June 24th, 2022 at 9:59 PM
So your classic telephone is actually a pretty simple device. Basically the phone line always as a voltage, around 50 volts DC when it's on the hook, about 9 when it's off the hook and around 110 when it's ringing.
it's a simple 2 wire connection, what we call twisted pair... there's a reason ethernet is based on it with similar connectors, it's a hold over from the companies using RJ11 cables and RJ9 before that.
you have 3 kinds of phone cables, RJ11 for a single line, RJ14 for a double, and RJ25 for a tripple.
the wiring diagrams are pretty simple and all 3 share the same wiring layout however there are 2 main standards you need to look out for, the old US Bell standard, and the 25 pair color code that began making the rounds in the 50's onward. Each has a pair of wires, + and -, also known as Tip, and ring. if that sounds familiar you'd be right, they correspond to a mono headphone jack, tip for voltage, ring for ground.
in the old system
Line 1 is Red for ring or ground, and Green for voltage or signal.
Line 2 is Yellow for ring, and Black for signal.
Line 3 is Blue for ring, and Orange for signal.
Now in the updated 25 pair color code this was changed to a pair of stripped cables, two of the same color but one is the inverted color.
White-green +
Green-white -
White-orange +
Orange-white -
White-blue +
Blue-white -
Why the blue one is reversed I have no idea, but on the wiring layout it's done in this order.
![[Image: xNehKPD.png]](https://i.imgur.com/xNehKPD.png)
When working on the payphone, the internal wiring for the handset used the old bell wiring system. I don't know why it used an RJ14 wiring setup to separate the microphone and ear piece but it does. in my case for whatever reason the signal line was buzzing so I had to ground it to the frame...
It gets more interesting however when you get to punch boxes or Telco boxes.
![[Image: 7hkNLBBl.png]](https://i.imgur.com/7hkNLBBl.png)
These basically just have the wires punched onto those little plug ends with a wire punch tool.
You'll no doubt have noticed there's a 4th wire color pair. Some phones systems have a 4th or even 5th line to them. and use the 25pin standard which has a whole chart.
Brown-white -
White-brown +
Slate-white -
White-slate +
simplify there's 5 sets of 5 with the white being the first five, red being the second, black being the third, yellow being the 4th, and violet being the 5th. You probably won't see any of those outside telco boxes though
[spoiler=Telco wiring diagram/color code.][/spoiler]
This also looks similar to an RJ45 ethernet connection. To make things more confusing they use the same wiring color pattern but have the ground wire solid and the voltage wire stripped. Bonus: if you swap the orange and green solid, then the orange and green stripped wires, you've just made a crossover ethernet cable and can connect 2 PC's together.
Finally, those cable punches serve two purposes, quick and easy repair of phone wires on site. And making it easy to test the lines.
for that you'll need one of these.
![[Image: uIvvWmKm.png]](https://i.imgur.com/uIvvWmKm.png)
This is known as a Butt set or linemen's telephone.
Those weird alligator clip looking things are a special version of an alligator clip called an ABN or Angled Bed of Nails clip. It's designed to latch onto those punch wire connectors and tap into the phone line at these boxes. It also has a nail type thing in it to poke directly into a wire and tap into it that way if you don't have a telco box.
Yeah, anyone who can hook up two wires to a twisted pair can tap into it, it's unencrypted... but you'd need to break into a phone box or dig up a phone line to do it which has some pretty hefty fines in most countries. Phone phreaks used to do stuff like this back in the day often to use someone else's lines for their explorations and phreaking stuff.
You can also make your own lineman's telephone set for around $20 by ordering the alligator clips, buying a phone cable, and cutting up any old POTS telephone.
anyway that's phones from the perspective that everyone is likely familiar with or has seen. I'll answer any questions people might have since this is only the tip of the ice berg and I haven't gone into telephone exchanges and such.
it's a simple 2 wire connection, what we call twisted pair... there's a reason ethernet is based on it with similar connectors, it's a hold over from the companies using RJ11 cables and RJ9 before that.
you have 3 kinds of phone cables, RJ11 for a single line, RJ14 for a double, and RJ25 for a tripple.
the wiring diagrams are pretty simple and all 3 share the same wiring layout however there are 2 main standards you need to look out for, the old US Bell standard, and the 25 pair color code that began making the rounds in the 50's onward. Each has a pair of wires, + and -, also known as Tip, and ring. if that sounds familiar you'd be right, they correspond to a mono headphone jack, tip for voltage, ring for ground.
in the old system
Line 1 is Red for ring or ground, and Green for voltage or signal.
Line 2 is Yellow for ring, and Black for signal.
Line 3 is Blue for ring, and Orange for signal.
Now in the updated 25 pair color code this was changed to a pair of stripped cables, two of the same color but one is the inverted color.
White-green +
Green-white -
White-orange +
Orange-white -
White-blue +
Blue-white -
Why the blue one is reversed I have no idea, but on the wiring layout it's done in this order.
When working on the payphone, the internal wiring for the handset used the old bell wiring system. I don't know why it used an RJ14 wiring setup to separate the microphone and ear piece but it does. in my case for whatever reason the signal line was buzzing so I had to ground it to the frame...
It gets more interesting however when you get to punch boxes or Telco boxes.
These basically just have the wires punched onto those little plug ends with a wire punch tool.
You'll no doubt have noticed there's a 4th wire color pair. Some phones systems have a 4th or even 5th line to them. and use the 25pin standard which has a whole chart.
Brown-white -
White-brown +
Slate-white -
White-slate +
simplify there's 5 sets of 5 with the white being the first five, red being the second, black being the third, yellow being the 4th, and violet being the 5th. You probably won't see any of those outside telco boxes though
[spoiler=Telco wiring diagram/color code.][/spoiler]
This also looks similar to an RJ45 ethernet connection. To make things more confusing they use the same wiring color pattern but have the ground wire solid and the voltage wire stripped. Bonus: if you swap the orange and green solid, then the orange and green stripped wires, you've just made a crossover ethernet cable and can connect 2 PC's together.
Finally, those cable punches serve two purposes, quick and easy repair of phone wires on site. And making it easy to test the lines.
for that you'll need one of these.
This is known as a Butt set or linemen's telephone.
Those weird alligator clip looking things are a special version of an alligator clip called an ABN or Angled Bed of Nails clip. It's designed to latch onto those punch wire connectors and tap into the phone line at these boxes. It also has a nail type thing in it to poke directly into a wire and tap into it that way if you don't have a telco box.
Yeah, anyone who can hook up two wires to a twisted pair can tap into it, it's unencrypted... but you'd need to break into a phone box or dig up a phone line to do it which has some pretty hefty fines in most countries. Phone phreaks used to do stuff like this back in the day often to use someone else's lines for their explorations and phreaking stuff.
You can also make your own lineman's telephone set for around $20 by ordering the alligator clips, buying a phone cable, and cutting up any old POTS telephone.
anyway that's phones from the perspective that everyone is likely familiar with or has seen. I'll answer any questions people might have since this is only the tip of the ice berg and I haven't gone into telephone exchanges and such.
