Header Ad Module



No announcement yet.

telephone jack wiring

  • Filter
  • Time
  • Show
Clear All
new posts

  • telephone jack wiring

    Hi. I have a legacy BT 3-wire telephone jack (plug socket) with 6 connectors (wall mounted secondary type). It has been working fine for many years for voice & data with a DSL filter on it. The telephone & fax work well with no static & the internet works fast with no disconnects, etc. The plug on the telephone wire that goes into the wall socket is a BS 6312 with 4 pins of the 6 having connectors (its the wide type).

    However, I now have a new HP networked printer/fax machine that comes with what looks like a filter splitter telephone wire. It's a telephone wire that goes from the printer into the wall outlet. The end for the wall outlet has a little box with a male & female for the same BS 6312 type plug. You plug the telephone wire provided with the printer into the telephone wall socket, and then there is a socket to plug your telephone wire into. Using their plug works fine for the fax on the new printer, but my phone line & internet do not work through their plug.

    In looking at the internal wiring of the BT 3w wall socket, it does not seem correct, even though voice & data have been working well. The same colour wires are connected together, which seems wrong.

    The Telecom wall wires are 2 sets of 4 wires each-- blue, green, red, white (no stripes on any wires). They are connected as follows: both white wires (one from each of the Telecom leads) are in slot 5, both green wires are in slot 2, and both blue wires are in slot 3, and the red wires are unconnected and left free dangling around.

    I've been searching online for the correct connections but get conflicting information. I believe connector slots 2 & 5 are the important ones for voice & data, with slot 3 being for earth maybe, and slots 1, 4 & 6 unused. I am wondering if for my situation, the green and the white wires are the important ones and whether there should be a green wire in each of slots 2 & 5 and also a white wire in slots 2 and 5. Then both blues could go into slot 3??

    If anybody knows or has ideas about which colour wires should go where, I'd be grateful.

    Sorry for the long post, I just wanted to include all details.


  • #2
    The colours of the wires are irrelevant, especially since every telecom sparky seems to use a different combo.
    Traditionally red & white are your line wires with blue being the "ring" line (as in Bells, not earth as you mention) with red on 2 being "nominal +50v", white on 5 being "nominal -50v" & blue on 3 having AC 200v when ringing (200v is also present between 2 & 5).
    But in your case, perhaps because in the past there has been trouble with a broken red wire, someone has used green in place of red, which is fine.

    Dont go messing with the wiring, that is not your problem.
    (I cant understand why you would want a green & white wire in the same connector, you would either be shorting out the line if they were on the same cable, or you would be reversing the loop forward to the next socket which is obviously somewhere else in the building)

    The problem is that the wire looping through the fax is not made for passing the internet connection.
    you need to use a phone/ internet DSL splitter/filter just the same as you presumably have been to date.
    plug the DSL splitter/filter into the wall.
    plug your internet modem into the modem socket in the DSL splitter/filter.
    plug the fax into the phone socket of the DSL splitter/filter.
    plug all your phones into the Fax "splitter" box if possible.

    the purpose of the box on the fax cable is to put your phones in series with the fax, so that if a fax is in progress, then someone picking up the phone will not corrupt the fax signal, since the fax disconnects the phones when a fax is in progress.

    If you have phones elsewhere in the building, you have 2 choices.
    rewire the building phone wires so they go via the socket you are using for the fax.
    if you dont use the fax very much, then just be aware when a fax is in progress, & make sure everyone stays off the phone at that point.
    Last edited by Keithw; 18-01-2012, 05:05 PM.


    • #3
      Keithw -- Thank you very much (again) for such detail.

      I'll follow your wise advice and leave the telephone wiring alone. I just need to connect the proper filters in the proper sequence. What you said about the phone wire that came with the printer is probably filtering out the internet in favor of the phone & fax, makes sense. So I'll plug a DSL filter/splitter into the wall as you suggest, and then plug my phone and new fax on the phone side of the splitter and the internet on the DSL side. This makes a lot of sense. I got thrown by thinking that the new cable was a DSL splitter when in fact it is probably just a phone/fax interrupter thing as you said.

      Big help! Many thanks.


      • #4
        What a splendidly diverse lot of helpful
        people we have on PropertyTalk, eh?
        Thanks, for helping, Keithw. All helps
        make these forums a great place to visit.
        Want a great looking concrete swimming pool in Hawke's Bay? Designer Pools will do the job for you!


        • #5
          Originally posted by Keithw View Post
          Traditionally red & white are your line wires with blue being the "ring" line (as in Bells, not earth as you mention) with red on 2 being "nominal +50v", white on 5 being "nominal -50v" & blue on 3 having AC 200v when ringing (200v is also present between 2 & 5).
          Just for correctness (Keith has covered this well) - it is not +50V and -50V (this would imply 100V between the 2 wires). One wire is 0V (not really earth but ...) and the other is -50V. The ring is generally around 85V RMS (200V would create an electrical hazard).