B.T. & U.S. Telephone Connectors.


B.T. Telephone Connector (Plug)
B.T. Pin Number
(above)
B.S.
Pin Number
Signal
Description
Standard
Wire Colour
Alternate
Wire Colour
1 6 Not Used (No pin) (White/Green) -
2 5 Line A White/Blue Red
3 4 (Local Earth) White/Orange Blue
4 3 Bell Shunt Orange/White Green
5 2 Line B Blue/White White
6 1 Not Used (No pin) (Green/White) -
Source:U.K. Telecom FAQ and Secondary Socket Installation Instructions
Warning:A D.C. voltage of around -50V exists between pins (B.T.) 5 & 2!

B.T. to U.S. Telephone Adaptor
(For U.S. Modems)
B.T. (B.S.)
Pin Number
RJ11 4C/6P
Pin Number
Wire Colour
2 (5) 4 Blue
3 (4) 5 Red
4 (3) 2 White
5 (2) 3 Green
(By inspection of adaptor cable Maplin (MPS) part no. RZ75S)

Prepared by F.T. Gowen
Last modified: 17th. May, 1999


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