US phone wire schematic

[tawa]

I didn't know where to post this, there isn't really a Misc section.

I'm having trouble getting my phone to work in my new house in the US. I had to wire in a new phone jack (wall jack) first. The phone company says they get a dial tone at the box outside the house. When I plug in my phone I get nothing. There are 4 wires in the wall. All I did was wire the red wire to a connection on the wall jack which also had red wires. I did the same with the other wires.

I think there are red, green, yellow and black wires. (Please correct me if I'm wrong. I'm in the US.)

The wire ends were very corroded, I will try to cut them off and get clean copper ends to wire to the new jack.

Next, what is the purpose of each wire?

When I see wiring schematics which use + and - from the phone, which wire is +?

Which is -?

What are the other wires used for?

Thank you!

[Opera House]

Once upon a time they were used for something, but now only the red and green are used.  If this is an older home it may have one of the very old surge protectors that has corrosion on it.  I had to take mine apart a couple of years ago when my line was really noisy.  Called the telephone company and now they charge for that work.  Not only that, but it would take more than a week.  I unscrewed this cap and some pellets and metal disks came out.  Don't remember exactly. Just cleaned them up and put it back together.  Red should be positive.

[Barnac]

Hi, have a look at those sites, they may help.

http://www.naturalhandyman.com/iip/inftelephone/inftel1.shtm

http://www.handymanusa.com/questions/wirephonelineq.html

barnac

in a stupidly cold montreal today -24°C (-11°F) with wind factor -34°C (-29°F)  

[Walt]

tawa, the four wire are used when you have two different phone numbers on the same jack. red/green is for the first line and the yellow/black is for the secound line. the green wire should be the positive and the red the neg. if the box on the outside of the house is new, also known as a NID (network interface device) it should have a jack type connection inside of it that you could plug a phone directly into it to test for dial tone. if it dosn't you can use a volt meter to check for voltage. it should read between 48 and 52 volts. sometimes the wire in the house is looped from one jack to the next and you may have a loose connection somewhere. one other possibility is that the jack could be bad, usually the tiny wires in the jack plug sometimes get bent and end up in the wrong slot inside the jack which will cause you not to get a dial tone.

hope this helps.

Walt

[wooferhound]

I remember back in the 1960's, that the yellow wire was the ringer wire. The phone company was charging for any extra phones in the house, and could tell if you had extra phones by how much ring current was being pulled. At that time I would add my extra phone but I would not hook up the yellow ringer wire to fool the phone company.

[tawa]

Thanks. Got new jack, rewired nice and tight, still no dial tone. Can't find NID on outside of house anywhere. There is a metal power box with a double breaker in it, that is lockable. Did not take off the inside plate to search behind it. But that is the same area where the phone wires come into the house. Wires (phone and power) actually go to attic. (House is single level ranch, with slab foundation. No crawl space.)

Called in to SBC (telco), their computer ran a self-diagnostic and said there was line trouble (which means at or outside of the NID). Phone system (not a person) said a tech would be out by  7pm EST today. We'll see what happens.

But I did test all 4 wires and there are no shorts. Nor could I find any voltage at all on any pair of wires, no matter what combination of wires I used for + and -. I even checked for AC! (One webpage said power is DC.)

[tawa]

Woof, that's interesting, as there are only 3 wires in my house after looking more closely. Red, yellow, and one that is so dirty, I can't tell if it's blue or green. Yes, even the copper UNDER the sheathing is corroded. I had to sand the copper to get a good connection. But, that's all moot as I could not find current on any combination of wires.

[tawa]

Correction, there were only 3 wires, red, yellow, and dirty.

[ghurd]

Try each one to a good ground. Might tell you which one is bad.

Should be a DC voltage to ground. 48 to 60 volts?

I did some design for a telephone device a while back.

'Ring Equivilent Number', or REN should get some good, in depth, info.

G-

[Peppyy]

If you are in the US there is an interface on the building. This should be a olive green or grey plastic box. It should have a regular screw on it that is labled customer access. If you don't see one where the phone cable goes into the house then I believe the phone company must provide one. Many times there will be only 1- 2pair wire from this box into the house, usually into the room where the electrical pannel is located.

If it is a really old instalation you should see something that looks like a large silver can near the service enterence.  The top or silver part comes off by loostening a retaining screw on the base. Inside there will be 2 long fuses. They could be corroded or worse missing. In this case the phone company should replace the entire unit with a modular one.

If it is an older house there is a good chance that they used a screw type terminal block to connect the wires to. You may find several wires hooked together. Determine which one comes in from the interface and isolate that one. Check that one with your meter.

If it is a really old house the wires inside have most likely been discontinued and a new wire will need to be run from the interface.

Good Luck.

[stm]

it's 48 volt until somebody is calling your number - then the volt will be raised to either 120 or 110 volts, which makes your phone start ringing. there's not much current, but it hurts a little anyway if you are'nt prepaired.

/Steffen