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From: Julian Macassey <julian@bongo.uucp>
Subject: British Telecom Auxiliary Jack Wiring
Date: 10 Oct 90 14:59:26 GMT
Organization: The Hole in the Wall  Hollywood California U.S.A.

In article <>, (Toby
Loftus) writes:

> I have a friend who is going to the UK soon and has a modem which will
> support CCIT (?) protocols, which I understand are used in the UK.
> What I would like is any information on how to physically connect the
> modem to the UK outlets.  I'm told that the UK has modular plugs, but
> ones quite different from US plugs.  Any suggestions on how to attack
> this?  Any company out there which supplies cords with a UK plug on
> one end and a US plug on the other?

	I suppose this should become one of this groups "Frequently Asked 

	Below is a file I keep on this matter. I hope it helps. Yes, I
know various countries have silly protective regulations about what
you can do with the service you are paying too much for. But I am
interested in telecommunications not restrictive practices.

               British Telecom Auxiliary Jack Wiring

        British phones have 3 wires. There are two wires A & B (Tip & 
Ring) coming into a house. There is no protector. In the primary jack 
in the house is a 2 uF capacitor. On the end of this cap is the third 
wire. The AC ringing signal is fed to the phone on  this wire and its 
DC counterpart. See diagram:

                  ----| |------O (3)
    (A) O----------------------O (2)

    (B) O----------------------O (5)

        Note:  The Numbers in the diagram are the numbers engraved on 
the jack terminals. If the phone rings continuously, reverse 2 and 5. 
The ringer is fed by AC current on pins 3 and 5.

        BT  consider the A terminal to be ground. B is measured as 45 
to 50 volts above ground.

        Wiring Colour Codes:
        The standard inside wire is classic "3 pair". A jack is wired 
as follows:

        Pin #               Wire colour

        2                   Blue/White
        3                   Orange/White
        4                   White/Orange
        5                   White/Blue


	So if you have a US device that you need to wire into a UK jack this 
is what you do. Get a US line cord and cut the jack off one end. Go to 
your local UK electrical shop and have them terminate the end with a 
UK jack. The center two wires in a US line cord are the phone line, so 
they should terminate on UK jack pins 2 and 5. Then you plug the UK 
end into the wall and the US end into your phone, modem, answering 
machine etc.

	You can also buy a line cord with a US plug on one end and 
spade lugs on the other. Using a screwdriver you screw the line cord 
onto the terminals in a jack or junction box. This works all over the 

Julian Macassey, n6are  ucla-an!denwa!bongo!julian
N6ARE@K6IYK (Packet Radio) [] voice (213) 653-4495

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