What are master sockets?

Modified on Sat, 28 Mar at 9:52 AM

This article explains what a master socket is, the different types available, and how to arrange for one to be moved, replaced, or installed.

What is a master socket?

Your master socket is the point where the external phone line enters your premises. It is a white plastic box built into the wall, usually found in the hallway or near the front entrance. It is larger than any other phone socket in your premises and provides the strongest broadband signal.

All other sockets in your premises are connected to the master socket through extension wiring. This wiring is not designed to carry broadband signals reliably and can become damaged over time. For the best performance, always connect your router to the master socket.

Your master socket can also be used to identify faults with your internal wiring, especially if it has a test socket behind the faceplate.

What type of master socket do I have?

There are two types of master socket:

Standard master socket: Has one port on the front. You will need to use a microfilter to separate your phone and broadband signals. A microfilter must be connected to every socket in use at your premises.
Pre-filtered master socket: Has two ports on the front. Your phone and broadband signals are already separated, so you do not need microfilters.

Comparison of a standard master socket with one port and a pre-filtered master socket with two ports.

Can my master socket be moved or replaced?

If you need to move your master socket to a more convenient location, or it is damaged and needs replacing, an engineer visit can be arranged. There is a charge of up to £120 to move or replace a master socket. If Openreach assistance is required, this charge will increase.

Can I have a new master socket installed?

If you do not currently have a master socket, one can be installed. There is a £65 engineer charge for installation. If Openreach assistance is required, this charge will increase to £120.

I cannot find my master socket

Not all properties have a master socket. Some have a junction box instead. A junction box is a small metal or plastic box that connects to a single phone socket and has a non-removable faceplate. If your premises has a junction box, it is unlikely that you have a master socket. A master socket can be installed if needed - see the section above for details and charges.