In deep water with ISDN / Broadband install

Discussion in 'Broadband' started by Mike Faithfull, Oct 20, 2007.

  1. I'll try to make this as concise as I can, but it may ramble a bit. Please
    be patient 'cos I really would be grateful for help ...

    Friend has existing BT analogue telephone line (let's call it Line A)
    He also has, allegedly, a company-provided "ISDN line on a different
    telephone number"
    He's just changed employers and the "ISDN line" will be removed shortly, he
    He's also just signed up to have broadband on his Line A
    I went to his house yesterday to see if we could make use of the "ISDN line
    wiring" (instead of laying out additional wiring) to get his Line A extended
    to his upstairs office

    That's when I started to get confused ...

    There is only one BT cable coming into the house from the BT junction box
    The "ISDN line" seems to be on the extension wiring off that same line.
    That is, originally (pre-ISDN installation), the BT line (Line A) had
    extension wiring connected to provide an additional telephone point
    upstairs. In the upstairs office, this wiring has been cut before it
    reaches the outlet box and instead now connects into some sort of powered
    box (with a pulsating green light on the front !!) which then feeds a
    modem-type box with sockets to connect to his laptop computer and a

    So, despite having a "different telephone number" is the ISDN service
    presented on the same physical copper wires as the Line A service? (how can
    that work then?) and will the BT exchange (or BT technicians, or both!) get
    horribly confused if they try to set up his broadband service on his Line A
    telephone number if his past employer forgets to cease the ISDN service
    (which on past evidence they might well do!) on the same line ??

    Oh, there's a further confusion in that the incoming line seems to be
    connected directly to the removable front plate of the master socket -
    plugging the telephone into the 'internal socket' that's revealed when the
    front plate is removed leaves us with a completely 'dead' phone. I thought
    that couldn't possibly be correct, but then wondered if it was something
    caused by having the "second line for ISDN" on the same wires ... (oh, and
    finally, the Line A telephone that connects to the master socket doesn't
    have any kind of filter but still works fine without any hissing or
    whistling from a high frequency signal)

    Grateful for any help.

    From "Confused" of Hatfield, Herts.
    Mike Faithfull, Oct 20, 2007
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  2. Mike Faithfull

    ato_zee Guest

    Are you sure that only two wires are coming in?
    Off a pole can have two or more pairs.
    ato_zee, Oct 20, 2007
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  3. Mike Faithfull

    Bob Eager Guest

    It's probably a cable with two separate pairs in it. One for ISDN, one
    for the POTS (Line A) line. That's exactly what I have here.

    Does sound a bit of a hack job, though. When you say ISDN, is this true
    ISDN2e, or a Home/Business Highway job? What does it say on the front of
    the box with the green light, and how big is it?
    Bob Eager, Oct 20, 2007
  4. Mike Faithfull

    Roger Mills Guest

    In an earlier contribution to this discussion,
    The "single" wire coming in has almost certainly got 2 or even 3 pairs of
    conductors in it - and can thus support two or more independent circuits -
    one for Line A and one for ISDN, etc. What appears to be an extension is
    probably where it splits into two circuits.
    Email address maintained for newsgroup use only, and not regularly
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    Roger Mills, Oct 20, 2007
  5. Mike Faithfull

    Graham Guest

    BT Home Highway was discontinued about a year ago.

    BT Business Highway will be discontinued March 2008, see:

    Both these are implemented with a (white) rectangular box about 6 inches
    wide by 8 inches deep by 1 inch thick - see: nearly at the bottom of the
    page. There may be different writing on the box to distinguish between
    Business/Home versions.

    ISDN2e still exists. It looks like: -
    about half-way down the page. With ISDN2e you only get a digital
    connection. If you want to connect an analog phone you need some extra
    equipment. Typically this would be a router with a POTS output. Whatever
    it is, it will not generally be supplied by BT.

    It is unlikely that the cable coming to the property has only two wires in
    it - almost certainly it has at least 4 - i.e. 2 pairs. Separate from the
    HH/BH/ISDN2e box there will be at least one conventional master socket.
    Wiring from this socket will run to the HH/BH/ISDN2e box and there may be
    other wiring to the master socket for the "Line A" service. Careful
    investigation of the incoming cable and any anonymous junction boxes would
    be worthwhile.

    It would also be worthwhile asking the decommisioning technician to explain
    the wiring before any is disconnected, to allow discussion of how best to
    re-use it. So it would be worth your while being present while the BT
    technician does the work.

    -- Graham
    Graham, Oct 20, 2007
  6. Mike Faithfull

    Bob Eager Guest

    Indeed. But it might be Business Highway.
    Indeed. I didn't want to complicate the issue. More likely to be an
    NTE8...proper ISDN2e, which is what I have.
    Bob Eager, Oct 20, 2007
  7. Mike Faithfull

    Graham. Guest

    I think you actually have is just an ISDN line, nothing else.

    Typically Basic Rate ISDN is used to provide:
    1) a dedicated 128kbs data line, no POTS
    2) 1X64kbps data + 1POTS
    3) 2 separate POTS, no data

    So the incoming line (which will just be dead if you connect a POTS a phone
    to it)
    goes upstairs to the ISDN NTE, the box with the line-powered light.
    A pair of wires from one of the POTS terminals in the NTE goes to
    the phone socket, and also back downstairs to the other POTS
    socket, but this is a different pair to the incomming ISDN, but
    it may well be in the same cable.

    Different DDI/ MSN numbering is quite normal.
    Graham., Oct 20, 2007
  8. Lots of interesting information received, thanks everybody! I'll try to
    answer the questions, if I can, but first, let me assure Graham that there
    was a POTS service in existence before the ISDN came along, and it still
    exists with the same telephone number as it always had, and the 'phone is
    still plugged into the same master socket that it always was. I can quite
    believe that there are two pairs coming in to the master socket, but if
    that's the case, I still don't understand how they are connected.

    The NTE (whatever that means) is about 6 inches square, and about an inch or
    so thick, and AFAICR there's no obvious legend on the front, only this green
    light that 'pulsates' rather than flashes, if you see what I mean - it sort
    of "fades up" and then "fades down" without ever turning off, at about one
    cycle per second. I would guess that it's a "proper" ISDN not a Home
    Highway as it was provided by one of the high street Banks. I only got
    blank pages from but none of the
    pictures on the page looks
    like anything I've seen before.

    Graham said "It would also be worthwhile asking the decommissioning
    technician to explain
    the wiring before any is disconnected, to allow discussion of how best to
    re-use it. So it would be worth your while being present while the BT
    technician does the work" I had kind of expected that the supplier -
    whether by that I mean BT or the Bank, or both - would judge that it would
    be more costly to de-install the equipment than it would be to just abandon
    it (as the Bank has with the desk, chair, and HP printer/scanner/fax jobbie
    they provided - the only thing they wanted returned was his laptop computer)
    and disconnect the line at the exchange. If it IS 'decomissioned' the only
    person likely to be present is his elderly Mum, and she can barely speak
    English so getting any useful information from the Tech is pretty unlikely!

    I rather suspect this is all academic, and eventually I shall end up
    disconnecting everything from the master socket, identifying the POTS line
    from the jumble of wires therein and re-connecting it in the "normal
    configuration". Don't tell BT !!
    Mike Faithfull, Oct 20, 2007
  9. Mike Faithfull

    Graham. Guest

    You may be correct, but it is also possible that the POTS line
    was converted to ISDN with the configuration that I have
    suggested and the original number retained for the POTS
    phone. This will also explain why the original master socket
    has no dialtone, the engineer left it in place instead of
    replacing it with a junction box.

    The thing that makes me think I may be wrong, and there
    is indeed a separate POTS line, is you saying that you
    have successfully got ADSL provisioned on it. Is that
    signed and sealed?
    Graham., Oct 20, 2007
  10. Signed, sealed, but not yet delivered - i.e. an acknowledgement letter
    confirming payment details, account name / password etc. has been received,
    but he's waiting confirmation of BT putting the broadband signal on the line
    Mike Faithfull, Oct 21, 2007
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