How to connect your UK BT telephone

Master and Extension sockets are identical except that the Master socket has additional components:
A gas-discharge voltage-surge suppressor.
A 4k7 resistor to "loop the line".
A 1u5F capacitor to pass ringing current but not d.c.

Connect incoming line wires to terminals 2 and 5.

Wire extension socket to master socket by wiring terminals 2, 3 and 5 together.
2 and 5 should be a twisted pair since these carry the voice. 3 is used to disable ringing when the handset is lifted.
Cable colour convention:-
Blue with white tracer = 2
White with Blue tracer = 5
Orange with White tracer = 3

Fit socket so that plug clip fits on the right side. The sliding cover should slide upwards to open.

Plug has a spring clip to keep it in the socket. The clip is designed to break if someone pulls- or trips over- the cable.

A cord with plug can be fitted to the old fashioned "746" telephone as shown in the sketch.