ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
Unusual Well Pump Switch Failure
by gfretwell - 10/28/20 12:50 PM
Look at this mess...
by InspectorE - 10/27/20 09:09 PM
New tool
by gfretwell - 10/24/20 11:09 AM
Where is Everyone?
by Bill Addiss - 10/17/20 07:04 PM
New in the Gallery:
Facebook follies, bad wiring
FPE in Germany pt.2
Who's Online Now
1 registered members (gfretwell), 22 guests, and 14 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Page 1 of 2 1 2
Telephone pics #133473 08/11/02 04:11 PM
Joined: Aug 2001
Posts: 7,520
pauluk Offline OP
By way of something a little different, I thought some of you might find these pictures of interest.

Up until the early 1980s, the GPO (General Post Office) had a monopoly on telephone service in the U.K., the only exceptions being the historical quirk of an independent system in one city - Hull - and in the Isle of Man, which is self-governing in many respects. (The Channel Islands were also independent, but strictly speaking they're not part of the U.K.)

This is a Post Office type 746 telephone, installed as the standard instrument in the late 1960s & 1970s. It differs only slightly from the earlier 706 model which was introduced in 1959.

As such it was practically the British equivalent of the ubiquitous Western Electric 500 in the Bell System.

[Linked Image from]

Those of you familiar with the WE 500 will notice a somewhat different internal layout:

[Linked Image from]

[Linked Image from]

The range of colors available included a couple of two-tone schemes -- Green and gray.

[This message has been edited by pauluk (edited 08-11-2002).]

Test Equipment:
Large Selection of Test Equipment For Electrical, HVAC, Test & Measurement
Large Selection of Test Equipment For Electrical, HVAC, Test & Measurement
Re: Telephone pics #133474 08/12/02 12:53 AM
Joined: Apr 2002
Posts: 2,527
Bjarney Offline
I sorta' like Hyacinth Bucket's white slimline with last-number redial.

Re: Telephone pics #133475 08/12/02 05:09 AM
Joined: Dec 2001
Posts: 2,486
Texas_Ranger Offline
Hmmm... In Austria our Post had the monopoly on phone services until 1998. Until around 1995 every piece of equipment connected to the phone lines had to be listed. No wonder it took some time until new equipment could be imported and legally used...
In Germany in the 80ies (and maybe here as well) they had quite some trouble with imported modems. Unlisted modems were usually 2 or three generations faster ( 9600 bps instead of 2400) and way cheaper than the listed ones.

Re: Telephone pics #133476 08/12/02 06:53 AM
Joined: Oct 2000
Posts: 5,389
sparky Offline
all i can think of is the phone the piro
( played by Donald Sutherland) made a bomb of in the movie Backdraft.......

Re: Telephone pics #133477 08/12/02 08:32 AM
Joined: Aug 2002
Posts: 1,081
ThinkGood Offline
Greetings from the USA.

Here's a site you may find useful:


Re: Telephone pics #133478 08/12/02 09:44 AM
Joined: Aug 2001
Posts: 7,520
pauluk Offline OP
Hello, & welcome to the forum.

Thanks for the link -- I already found the NavyRelics site a few months ago, along with several others. I've probably spent more hours than I should have done listening to the narrated recordings on the Phone Trips site as well, but telecoms is a particular aspect of the electronics field that has always fascinated me (I used to work the phone co. over here).

I sorta' like Hyacinth Bucket's white slimline with last-number redial

Sounds like we have a PBS fan here! The 746 phone is more "Are You Being Served?" era. [Linked Image]

I don't think I know that movie. If it involves telephones, I should!

The modem situation you describe is pretty much how it was in the U.K. as well. There were certain Post Office modems, generally available for rental, and connection of any non-approved equipment was strictly "verboten" as you would say. That's not to say that certain people didn't do it, of course! (Why is everybody looking at me? [Linked Image])

Re: Telephone pics #133479 09/01/02 09:32 PM
Joined: May 2002
Posts: 381
Hutch Offline

I thought I would revive this thread with some pictures of the older type South African telephone plugs. The RSA now uses the USA standard.

[Linked Image from]

Each side of the outer two blades is electrically isolated plus two more surfaces in the centre, i.e. a potential total of three lines.

I know you'd want to peek inside so ...

[Linked Image from]

Line 1, Green and Red
Line 2, Black and Yellow

not connected,

Line 3, Blue and White

Re: Telephone pics #133480 09/03/02 10:26 AM
Joined: Aug 2001
Posts: 7,520
pauluk Offline OP
That plug looks a little like the Australian type. Interesting that the line is on the outermost contacts rather than in what would appear to be the logical adjacent contacts for each pair.

Has the RSA used the standard American colors (red/green, yellow/black) for a long time, or is that a fairly recent development? Did they ever use British colors (i.e. tip & ring = white & red) ?

Re: Telephone pics #133481 09/03/02 11:24 PM
Joined: May 2002
Posts: 381
Hutch Offline
I have RSA telephone wire that is at least 15 years old and it is USA rather than UK in its colour scheme. I have no idea how long this has existed.

On the US standard the center pair of six pins are line one. Which contacts are line one on the UK 'phone plugs? The plugs are different [for USA guys] and maybe you could post a picture. I tried using a UK/USA adaptor last time I was in the UK to down-load email but it failed miserably. I suspect that the line protocols were not correct/the same.

Re: Telephone pics #133482 09/04/02 04:58 PM
Joined: Aug 2001
Posts: 7,520
pauluk Offline OP
The 431A BT plug has the line connected to pins 2 and 5, which are the outer pair contacts. The inner contacts are not designated for a second line. Pin 3 is used to feed the bells and as a bell-shunt to prevent tapping during (pulse) dialing. Pin 4 is not used in normal domestic wiring, but may be used as an earth for recall on PBX systems. (The same plug shell is used for the 6-way version and has extra outer contacts in positions 1 and 6.) I'll see if I can post a picture later.

The U.S. modular plug (often incorrectly referred to as an RJ-11 plug) has also made an appearance in the U.K. in recent years, but only for connecting the cord to the phone (or modem) itself, not for the wall jacks.

The problem is that with the flat in-line cord used with both BT and U.S. plugs, it means that if all four wires are carried through then the American-style jack on the phone has to be wired with the line on the outer pair of contacts, contrary to normal American practice. A true U.K. to U.S. adapter will connect BT outer pair to U.S. inner pair. The different configurations cause all sorts of problems to modem users.

The color coding for the standard 4-way jacks is:

2, red, blue-white (Line B, ring)
3, blue, orange-white
4, green, white-orange
5, white, white-blue (Line A, tip)

Red/blue/green/white are the colors in the phone cord. The others are colors for fixed wiring.

The wiring is not the same as on the old 1/4-inch jack or hard-wired system.

[This message has been edited by pauluk (edited 09-04-2002).]

Page 1 of 2 1 2


2020 National Electrical Code
2020 National Electrical
Code (NEC)

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman


Member Spotlight
L.I. New York
Posts: 99
Joined: August 2003
Show All Member Profiles 
Top Posters(30 Days)
Popular Topics(Views)
271,022 Are you busy
205,030 Re: Forum
193,139 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3