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Telephone (North America) Two lines

Discussion in 'Electronic Design' started by Jim Thompson, Nov 16, 2004.

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  1. Jim Thompson

    Jim Thompson Guest

    It's really a function of who pre-wired the house. My house is wired
    as (1), except for my office where I have two RJ11s, one with the two
    lines of voice and the other the fax (and DSL when I had it) line.

    ...Jim Thompson
     
  2. Hi, what's the usual way of doing two phone lines in North American
    residences?

    1) Using inner and outer pairs of an RJ11 connector?

    2) Using inner pairs of two RJ11 connectors?

    Or does it vary from place to place etc.?


    Best regards,
    Spehro Pefhany
     
  3. Tim Wescott

    Tim Wescott Guest

    Any, either -- single-line phones ignore the outer pair, dual line
    phones follow (1). Sometimes you'll see dual jacks that put line 1 on
    the inside of one jack and line 2 on the inside of the other so you can
    mix and match in various phenomenal ways.
     
  4. Boy, I hope I'm not treading into deep water.

    The RJ-11 is a wiring specification. The connector is a "modular connector."
    When you wire up a 4-conductor "modular connector" with the inner two conductors
    for exactly one phone line, it is called RJ11 or RJ11C. But! When you wire up
    a 6-conductor "modular connector" with the inner two conductors for exactly one
    phone line, it is also called RJ11 or RJ11C. But! When you wire up an
    8-conductor "modular connector" with the inner two conductors for exactly one
    phone line, it is again called RJ11 or RJ11C.

    So... technically, there is no "inner and outer pairs" for an RJ11 connector.
    There is only an inner pair, but it doesn't say which modular connector you are
    using.

    RJ14C is the two-line thing. It's the inner two conductors for the what is
    probably going to be the 'primary use' phone line and the next-outer pair of
    conductors for the other phone line. This applies to the 4, 6, and 8 conductor
    modular connectors.

    RJ25C is for .. you guessed it .. three wire-pairs. And it cannot apply to the
    4-conductor modular connector, obviously. But does apply to the 6 and 8
    conductor types.

    Finally, RJ48C applies to four wire pairs. I think RJ45 (I can't remember for
    sure) is for network connections.
    I think the standard IS a standard.

    Jon
     
  5. Dbowey

    Dbowey Guest

    Spehro posted:

    << Hi, what's the usual way of doing two phone lines in North American
    residences?

    1) Using inner and outer pairs of an RJ11 connector?

    2) Using inner pairs of two RJ11 connectors?

    Or does it vary from place to place etc.?
    The US Standard for two lines is a RJ14C "configuration". Physically it is as
    you describe.

    The RJ11 and RJ14 configurations both use a 6 position miniature modular jack
    and plug.

    Pins 3 and 4 are line 1 Ring & Tip, respectively.

    Pins 2 and 5 are line 2 Tip & Ring, respectively.

    I'm fairly certain that Canada uses the same arrangements, but with differently
    named configurations.

    As to "does it change from place to place?.... It can, because on the customer
    side of the NI the customer can do anything they want with jacks, plugs, and
    hard-wire. The Standard configurations are *required* only at the NI.

    Don
     
  6. Dbowey

    Dbowey Guest

    RE: "The RJ11 and RJ14 configurations both use a 6 position miniature modular
    jack
    and plug."

    But I intended to caution that although the ANSI
    Standard *requires* the specific jack, the plug is "advisory" except where it
    is provided within a telco owned NI box. As a result, some manufacturers used
    to, and still might, put pins at positions 3 and 4 of their packaged "RJ11,"
    but not in positions 2 and 5. The point is, you need to be careful when you
    order a plug and jack set.

    Don
     
  7. Ross Herbert

    Ross Herbert Guest


    You should be able to get answers here
    http://www.zytrax.com/tech/layer_1/cables/cables_jacks.htm

    Telephone wiring is usually done to the USOC wiring standard where
    pr.1 occupies the centre pins, pr.2 the two pins on either side of the
    centre and pr.3 where used the two outermost pins. These days where
    the 8 way modular connector serves dual purpose use as both lan and
    telephone the wiring conforms to either EIA/TIA 568A or B.

    As others have mentioned the use of RJ.. terminology is no longer
    correct and modular connector is the preferred term. Also, you will
    find terms such as 6P6C or 6P4C used. These refer to the number of pin
    positions in the connector (plug or socket) 6P in the above, followed
    by the number of pins actually fitted 6C or 4C. The usual standard for
    lan wiring is 8P8C where all 8 pin positions are equipped.
     
  8. Dave VanHorn

    Dave VanHorn Guest

    It was never correct, when referring to the plug.
    It's a service order code on how to wire the jack.
    A 6 pin modular jack is simply that, not (and never has been) an
    RJ-Whatever.
     
  9. Rich Grise

    Rich Grise Guest

    Some years ago, I had a home office with RJ-14 jacks, with the panels
    wired with 2112 on top and 1221 on the bottom. As it happened one day,
    I had a friend over and was showing her my laptop, and she promptly
    dialed in to the BBS that we were both members of. I sat at the other
    computer, which was AFAIK plugged into line 2, and as soon as my
    modem went off-hook, she got hung up on. The only thing I can think of is
    that the modem I was using did something to pins 1&4 when connecting - I
    don't specifically remember if I swapped the 4-wire cord for a 2-wire on
    the spot, but when I did, the problem went away. The old, old style 4-
    prong jacks used to use all four wires for something important, I seem to
    recall, although that could be just that the 2 were reserved for phone
    company use - I once saw the wiring in a guy's house that was so old that
    he still had the little telco wall wart for powering the trimline plugged
    in in the basement. It used pins 1&4 for lamp power.

    Things have no doubt improved considerably since then. :)

    I really just wanted to brag about having had a babe visit my office.
    <leer, snort>.

    Cheers!
    Rich
     
  10. Ross Herbert

    Ross Herbert Guest

    No argument from me on that. However, it is fact that despite what
    "never has been" the popular terminology "RJ.." was applied almost
    universally back 10 years or so. It will take a bit longer yet for the
    common usage to disappear.
     
  11. Dave VanHorn

    Dave VanHorn Guest

    The only thing I can think of is
    Ever hear of "A-Lead"?
    Many systems implemented this, simply a contact closure on a second pair, to
    support key systems that had a hold function.
     
  12. Dave VanHorn

    Dave VanHorn Guest

    Yup. :p

    I used to have one of those USOC books, I got it back when I was wrestling
    with GTE in Hawaii.
    We ordered RJ-31X jacks for alarm use, and I'd swear that they never wired
    one twice the same way, and never wired one right..

    We used to just take whatever they did, fix it back to USOC, and move on,
    until they threatened to sue us over it. Then we took them to the PUC, and
    explained our case. Many many wasted hours and trips to re-do their work,
    and no point asking them to fix it, they would either do nothing, or make it
    a different broken thing.... The PUC decided that we would "hands off" their
    gear, but they would be required to do it right from then on.. The next
    install saw SIX supervisors, who took most of a day to install the jack,
    pulled power from one operating computer to plug in their drill (to the
    extreme displeasure of the engineer using the machine) and damn near
    drilling through the power cord (220 or 440V) for the company's mainframe...

    After that, things got more serene, and they were wired right most of the
    time.


    Handy little book though, for resolving such disputes.
    Is it like this? No? Then FIX IT!.
     
  13. Tam/WB2TT

    Tam/WB2TT Guest

    6 pin modular jacks can be very confusing. It can be an 8 pin with 1 & 8
    missing, or an 8 pin with 7 & 8 missing.

    Tam
     
  14. Active8

    Active8 Guest

    What Tim said, Speff.
     
  15. Active8

    Active8 Guest

    <snip>[...]

    ISTM that the catalogs still call the different connectors by RJ
    numbers, no?

    At any rate, that was some interesting trivia, whether I ever use it
    or not.
     
  16. Yup, mucho thanks. I'm putting three modular jacks in to cover the
    possibilities. ;-)


    Best regards,
    Spehro Pefhany
     
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