I am trying to setup my new DSL modem and to save $100 a told AT&T that I would install the modem my self. The installer left open the box on the side of my house so that I could connect in, but I can't seem to get the coloring right on the phone line I bought to put an end on it. The box on the side of my house that I'm connecting into has open the black and yellow slot for me to pull data in. When I create the other end that plugs into the modem, I use the following color order:

Green  Red  Black  Yellow

That doesn't seem to work, so am I just supposed to put black and yellow together in the center or do I have the order wrong.

I am using phone line to do this, not CAT5. I'm also not sure if this was the place for the question, but I figured that it was probably the most likely to give me an answer.

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    The fact that you have to ask this question (which is off-topic here, as per our FAQ) demonstrates that you are not at all qualified to do this yourself. – Sven Mar 20 '12 at 15:21
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    Sven, if you look you'll see that this post was moved to Superuser from Serverfault. I have run countless feet of CAT5 in the past, so I figured that phone line couldn't be too difficult. – Dave Long Mar 20 '12 at 15:48

The correct order is Black, Red, Green, Yellow. It's important to remember that RJ11 has 6 pins, and you are using the middle four.

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  • I just rewired with this color code and i'm still not getting a signal through to the modem. I'm on the phone with my ISP and will post back with what I find soon. – Dave Long Mar 20 '12 at 15:41
  • @KyleSmith RJ-11 has two or four (aka RJ-14) pins. 6 pins has RJ-12 (aka RJ-25). Plugs are the same, though. – brownian Mar 20 '12 at 15:48
  • I think what he means if that 6P has 6 pins. – Dave Long Mar 20 '12 at 16:05
  • So it looks like I was wiring correctly, but the guy who wired from the pole to my house did his stuff incorrectly, so I will find out by the end of the day if black, red, green, yellow is the correct scheme for DSL lines. – Dave Long Mar 20 '12 at 16:07
  • Just check to see which pair the line is on with a voltmeter or phone. It should be on the read and green pair, but you never know. – David Schwartz Mar 20 '12 at 16:15

Phones only use the Green and Red pair. The Black and Yellow are for a second phone line in today's systems (and where for DC electricity to run old telephones back in the day).

  • It would seem that black and yellow are now used for data instead of more lines or DC current. – Dave Long Mar 20 '12 at 15:35
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    Dave - no. DSL runs on the same exact pair as the voice on a POTS line. – mfinni Mar 20 '12 at 16:35
  • DSL only runs on 2 wires; it'd be very strange to break them onto separate lines from the voice traffic. DSL essentially works by transmitting high frequency signals (sound if thats how you want to think of it) on the same lines as your normal voice traffic. – Chris S Mar 20 '12 at 17:08

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