The following pictures show the standard bt telephone wiring colour code used with the bt nte5 master socket. For information on non bt line cords click here.

Uk Telephone Wiring
Bt 431a plug wiring diagram. Click to check the right one for you or print as reference. Cord wiring bt supplied cords came in differing styles. A pair of bt plugs. The replacement cable i got has blue blue and white and orange orange and white. It plugs into the master socket and has a spare 431a connection at the bottom of this is a rj11 plug and the cable which came from that has a colour code white green blue and red. However the line is dead.
I tried wiring the new cable like this. Telephone wiring colour code bt nte5 master socket. 631a is used with 6 wire cordage. If the lead has a bt adapter at one end the colour swap is usually made there usr tended to swap it in the rj11 plug others do their own thing. Remember the rj45 wiring order. This is pretty much unique to the uk and comes in two types.
The bt telephone cable is an inexpensive piece of wiring with the actual cost of materials amounting to just a few pence per metre. Contrary to how it might seem c1 is connected to terminals 2 3 not 1 4. Click to find view print and more. Note that with the two rightmost 2 wire examples in the diagram going from rj11 to bt will involve the colour code going wrong at one end or the other unless a junction box or joint is used. Hi this video shows how to install a new or replacement bt plug. Please note you must use the correct inserter tool to push the wires in to the phone socket idc connectors.
Do not attempt to connect the old style round telephone lead to a plug no. Bt openreach are using new cables with new colour codes. The wiring diagram for a master lju socket is shown here. Rj45 pinout diagram shows wiring for standard t568b t568a and crossover cable. The old wiring scheme was as follows connector 2 blue with white rings connector 3 orange with white rings connector 5 white with blue rings this has now changed to connector 2 blue connector 3 brown connector 5 orange the ring wire or bell wire. Failing to do so will open the blades permanently damaging the connector.
431a is used with 4 wire cordage whilst plug no. The common ones are tabled below. 431a bt 4 way plug 6p4c 631a bt 6 way plug 6p6c the 4 way plug is the standard one used on home and small business telephones. The complete ethernet pinout cable wiring reference with wiring step by step guide. There are two different types of bt extension leads 431a and 631a and to tell the difference count the slots with copper wires on the phone plug. Both the 4 way bt431a and the 6 way bt631a are shown.
Note that the pictorial view shown above only serves to indicate the two differing types of sockets and wiring connections. In the uk the most common way of connecting a telecommunications device to the telephone line is a bt plug. The 4 way bt plugs are used in residential systems and the 6 way bt plugs.