| 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! | ||||
