We often need to ask people to check if a fault on their phone line, affecting either broadband or voice calls, is with the line itself or their internal extension wiring.

The distinction is important because BT own the wiring between your master socket and the exchange, and will turn out, test, and repair it free of any charge. BUT the wiring from the master socket, where the line first enters your house or office, to any extension sockets or other connected equipment, AND the equipment itself, be it phones, modems, fax machines, Sky tv box, etc. is yours. If BT turn out to look at a fault and they find the fault is with your device or with your cable (a) they will send you a bill and (b) they won’t fix it!

The test is simple enough and will take only a couple of minutes. All you need is a screwdriver.

You need to find the “master” socket. It may be your only socket. If you have more than one, look for the bigger one with a split across the faceplate.

When you unscrew the two screws, the bottom half of the faceplate comes easily away but careful, there may be wires connected to the back of it, which you should take care not to tug loose! ┬áThe picture here (borrowed from Wikipedia1) shows the faceplate removed with the cables to the back still attached. You can safely leave the faceplate dangling on the cable. Your internal extension wiring is now disconnected from the BT line. You can also see the “hidden” test socket bottom right, now revealed.

If you are testing a broadband problem, plug your microfilter into the test socket.

If you are testing a voice call problem, plug a known working phone in to the test socket.

If the problem continues, then it’s a problem with the BT line and we can safely call them out without fear of unexpected charges! But if the problem goes away, then the problem is with the extension wiring you just disconnected, or one of the devices connected to it. Call us, we’ll talk you through further tests to narrow down the culprit.

To reconnect your extension wiring, just offer the faceplate back to the remainder of the socket, slide it carefully in, making sure the cable isn’t trapped, and then put the two screws back.

1 – the photo in this post was borrowed from Wikipedia, where the copyright owner has stated that that is permissable – for the original photo including licence and a link to the photographer, please follow this link.