In this guide, we’re going to look at how to install a new telephone socket inside your home. It’s not about connecting your phone to the telephone network, as that’s a job that can only be tackled by your phone provider. It’s about putting another socket further inside, which you can connect a second phone or router/modem to.

Why install an extension telephone socket?

In today’s connected world, having access to a telephone and internet connection throughout your home is more than a luxury – it’s a necessity. An extension socket allows you to extend the reach of your existing telephone line to other areas of your home or office, providing the convenience of connecting phones or setting up a wired internet access point away from the main socket.

Although wireless phones obviously exist, this can be especially useful in large homes or in buildings where the wireless signal may not be reliable. Additionally, having multiple connection points is beneficial when you need to plug in devices that require a wired connection for more stable communication like a landline phone or a desktop computer. An extension socket also means you can strategically position your wireless router to optimise Wi-Fi coverage throughout your property.

How to install an extension telephone socket

Now, we’re ready to get going. Just note that this guide is applicable to UK users – phone lines on other territories may be different.

Warning: master socket installation

Before you begin, it is crucial to understand that the master socket – your primary telephone connection point often installed by a service provider – should only be worked on by a professional installer. Interfering with the master socket without approval may violate your service terms and can cause faults for which you might be liable.

Preparing for the task

To install an extension telephone socket, you’ll need some basic tools and materials:

  • An extension telephone socket
  • Cable clips
  • A screwdriver
  • A hammer
  • An electric drill (if required to pass cables through walls)
  • Wire cutters/strippers
  • A terminal or punch down tool (depending on the socket type)

Telephone sockets, just like light switches and power sockets, are available in a range of styles and finishes, such as anthracite, matt white and brushed steel.

Step by step instructions

1. Plan your route

Decide where you want the extension socket to be and plan the cable route back to the master socket. Avoid running cables parallel to electrical wires to prevent interference and choose a discreet path that won’t be a trip hazard or cause aesthetic issues.

Don’t run cables across the floor or under carpets – a good place to run them is along the top of skirting boards, or up the corners of walls, where they are less visible. They can be sunk into skirting boards or walls, but you’re creating a big job for yourself, with minimal aesthetic benefit. You might have to drill through walls or door frames when you run into a new room (or you can pass them under floorboards). Make sure the door can close without touching the cable.

2. Attach your extension socket to the wall

Once you’ve worked out where to put the socket and planned how your wire will reach it, you can install it. It’s a pretty simple process. Hold the pattress box for the socket in place, and mark where you need your drill holes if you’re going into a wall. Then drill your holes for wall plugs, and screw the backplate in place. If you’re attaching it to a skirting board, you can simply screw it into place with short screws – no need for drills.

Phone sockets can be sunk into walls, just like plug sockets, for a neater finish and lower profile than using a pattress box. It will be a much bigger job, however – most people prefer to simply hide the socket away behind furniture!

3. Measuring and cutting the cable

Once you’ve worked out the route, measure the required length of cable, adding a little extra for ease of connection and possible re-routing in the future. Cut the whole cable to length with wire cutters. You’ll probably find the cable has four wires inside it. You only really need two, and the extra two are placed in as standard, and could come in handy if ever you want a second line installed.

4. Attach cable to walls/ceilings

Use cable clips to secure the extension cable along the chosen route. Hammering these in place every 30–50cm should be sufficient. Ensure the cable is taut but not overly stretched. If you can’t hammer the nails in, i.e. if you’re not connecting the cables to wood, you can use other methods of connection, such as wall plugs and screws (for walls or plaster), cable ties, hooks or adhesives.

5. Drilling through walls

If you need to pass the cable through walls, carefully choose the location to avoid pipes and electrical wiring. Always check for wires and plugs using your housing plans and purpose-built wire detectors or scanners, which you can get from hardware stores. Use an appropriate drill bit for the wall material, and drill slowly to make a clean hole.

6. Connect to master socket

You must connect the extension cable to the appropriate terminals on your existing master socket faceplate. Depending on your setup, you may find extensions connectors on the front plate or behind it. It is advisable to use an NTE5 faceplate which allows easy connection without disturbing the main socket wiring.

Most master sockets have a second set of connectors inside them, which are there for homeowners to extend their cables – you are allowed to use these, as it shouldn’t affect the connection to the network or damage the connection. If not, you’ll have to extend the cables using the existing terminals, or purchasing a ready-made extension kit which simply plugs into the socket.

Each terminal will have a number on it (there should be six connectors). It doesn’t really matter which colour of wire you connect, as long as you connect the same colour to the same number at the extension. However, if you can copy the colours of the wires coming into the home, it makes things simpler for future modifications. 

Most UK telephone cables consist of four different coloured wires, but for single-line connections, you typically use only two (often the blue/white and white/blue pairs). Connect the wires to the corresponding terminals within the extension socket. Terminals 2 and 5 are the important ones, as they are the ones that your phone uses, but since you’ve probably got four wires, connect 3 and 6 as well. This is where you will use either a punch-down tool or a screwdriver, depending on the socket type. Push-down connections are considered better, as you don’t need to strip the wire and they provide a solid connection that won’t come undone. The copper wires in phone cables are quite small in diameter, and there’s more of a risk of damage if you use screw terminals.

7. Wiring the extension socket

Repeat the process at the extension socket, making sure you connect the same colours to the terminal with the same numbers, so if you connect blue/white to 2 on the master socket, connect blue/white to 2 on the extension socket.

8. Fixing the socket and testing

Make sure the extension socket is securely in place on the wall, and that no wires are trapped or pinched. Once everything is connected, you can test the line by plugging in a phone and checking for a dial tone.

9. Neat finishing

Ensure all cables are clipped in place and that excess wiring is neatly tucked away. A tidy installation is not only more visually pleasing but also reduces the risk of accidental damage to the cables.

Summary and safety checks

After installation, it’s essential that you double-check that everything is secure and that there’s no bare wiring that might cause a short circuit. As a final step, ensure that your internet and phone services are functioning normally and consistently.

Remember, while it is possible to install an extension socket by yourself, always prioritise safety and when in doubt, consult with or hire a professional to ensure the job is done properly and without risk to your home or your telephone services.