I have a new telephone jack to replace the old on the wall outlet. The new jack is confusing and I'm new to this. I think I may have messed with the wiring, and I don't understand which wire should go to which terminal. The purpose of the jack is so it can only connect to a ADSL modem and not for any phone. The telephone cable, is made up of two wires, blue and white. Heres how I connected to the new telephone jack:

enter image description here

As you can see, blue and white wire. And 4 terminals. On the jack itself, they are just numbered from 1 to 4. Im gonna guess these are L1, L2, TS, TX? Or does it mean something else? Each terminal has two holes. What i did was just connect to 1 and 2, because i didnt know what else to do. Was it supposed to be 1 and 3? or 1 and 4? The internet works after wired it, but the upstream is lower than before, 50% lower. Should I just leave it as is, as it probably doesnt matter which wire goes where?

Also side note, Ive shortened the thin wires I have because telephone jack screw system bends and nicks it. Should I not shorten it everytime I rewire? I now have a very short wire as a result and makes things difficult.

edit: heres a manual for the type of phone jack im using, look to the right of first page: http://e-catalogue.legrand.ru/upload/files/LE07456AB.pdf

and here is a video of someone installing exact same: https://youtu.be/m8ffHiIOzw0?t=87

  • ADSL is very sensitive to line noise and can be finicky. It sounds to me based on your comments that your wiring is OK but perhaps your jack is allowing some cross-talk or other interference. I'd post a real answer except I'm not knowledgeable enough to give any real info and don't have the time to research it, but if somebody else agrees I'd love to see a real answer. You could try a higher quality jack, perhaps one specifically designed for ADSL with a built in filter, or by adding a filter (bit.ly/2bHwFFR for example is a nice wall mount filter with a proper phone splitter output).
    – Jason C
    Commented Aug 22, 2016 at 18:35

2 Answers 2


You need to connect to the center two wires in RJ-11. Since RJ-11 is usually 6 pins, these are pins 3 and 4. If yours has only 4 pins, these should be pins 2 and 3. Leave the other pins unconnected.

Now, with regards to the colors (and correct polarity), this is country-dependent. Check this chart for reference. But, you can also try one way, and if it doesn't work, switch the wires.

  • 1
    RJ-11 has always been 4 pins. 6 pins is an RJ-25.
    – BillDOe
    Commented Aug 21, 2016 at 19:36
  • 3
    @BillOertell: If you want to be that precise, then, no, you're incorrect too. RJ-11 is one-line (two wires), RJ-14 is two-line (four wires) and RJ-25 is three lines (six wires), all using the same physical connector format. I haven't seen real RJ-11 in years, they all are either RJ-14 or RJ-25, but are called RJ-11 for simplicity's sake.
    – haimg
    Commented Aug 21, 2016 at 20:22
  • 1
    @Altoban If it's working now then what problem are you trying to solve?
    – Jason C
    Commented Aug 21, 2016 at 20:29
  • 1
    @Altoban Just asking the obvious first: Are you sure you seated the wires properly in the connectors? E.g. stripped the proper amount off the ends, proper insertion, turned the thingy securely with the screw driver, etc. Also have you tried swapping out a known good cable between the modem and the wall jack just to rule that out?
    – Jason C
    Commented Aug 22, 2016 at 0:52
  • 1
    @Altoban if it's working at all then you have to correct pair, degraded speed would be caused by introduction of noise or EMV. Incorrect wire?
    – Tyson
    Commented Aug 22, 2016 at 17:21

According to your graphic you supplied you have it reversed.The White conductor terminated on the 1 posistion, The blue on the 2.

  • You have the blue and white reversed.
    – user59172
    Commented Aug 22, 2016 at 19:52

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