Like many in the UK when they found out they could get superfast BT Infinity fibre optic broadband, I signed up right away. The fast speeds of upto 76mb down and 19mb up were too good to miss out on, particularly with the remote work for customers I do and lots of home working in my lab.


However I also did not realise that with the change from ADSL broadband to fibre optic broadband (BT Infinity), it meant [apparently] that the router (BT Home Hub and modem) could only be connected to the master socket.


Sure there is an extension kit BT can provide but that means tacking some cabling along the wall which I (and certainly my wife did not want). This was annoying because the house already had cabling for telephone extensions which the ADSL broadband used to use so I could locate the router in my office. But also the WiFi and/or ethernet over power adaptors I used to get the internet into the office slowed my superfast internet down from the actual 68mb I was getting to around 30mb with great variance and increased latency. This was annoying for me, while 30mb is lovely from 8mb internet it felt such as waste!



I looked around for answers and I always found information on the extension kit and people confirming it must to be connected to the master socket for BT Infinity. So I stuck with it at the master socket and the slower speed for about 6 months. Then I decided to research into how the new master socket works and the DSL cable from the master socket to the modem. It turns out the cable from the master socket to the modem is just a simple 1 pair copper cable with RJ11 termination at both ends. So I thought in theory if my existing household extension cabling was decent enough I could possibly send it over it to an extension somehow. Looking deeper I was surprised how easy this was and I will explain this below and what you need.



How to create a DSL extension socket from any existing telephone socket
I'm not going to explain how to move your master socket, that is not what you want to achieve and BT would not want you to do that either.
What we are going to do is extend the DSL connection (which the BT Home Hub and/or modem uses) to another existing socket in the house. The exact same way telephone extensions work.
This is allowed and possible because there is a DSL extension connector in the master socket to allow you to do this. So I repeat, you do not need to move your master socket to put BT Infinity in another room if you have existing extensions your ADSL used to use!



Time: Around 5-10 minutes

Difficulty: Easy (Some knowledge of very basic telephone cabling, your house and how to use a screwdriver)

What you need: A krone tool/small flat screwdriver, a telephone to RJ11 cable (Scroll down for image of this)


Firstly I should tell you the obvious, the socket you nominate to become your VDSL extension socket will no longer be a telephone extension socket, it will be for the internet only!

And this is only applicable for BT Infinity Fibre to the Cabinet (FTTC), not fibre to the home/premises (FTTH or FTTP).



1. This is what the master socket looks like. It's probably near your front door like mine is or somewhere which is inconvenient (hence why your looking at this article).

Top socket: Your BT Infinity modem or BT Home Hub 5 with connect directly to this with RJ11 termination connectors and the cable will have 1 copper pair inside it.

Bottom socket: Your telephone will connect in the bottom socket


2. Unscrew the front plate of the master socket.


You will see your existing telephone extensions go into this front plate, you may have one or several extensions like me.

Each extension one has 3 wires, mine were (blue, blue/white, orange).

This is where you need to figure out which set of wires is the one you want, in may case I could see where the cable ran so knew it was the office extension.

Pull out the wires for your required extension only.


3. If you look at the second part of your master socket, there will be a connector for 2 wires in the top left. This is the DSL extension connectors.


Take the 2 same coloured wires (in my case blue and blue/white), neatly rolling out the way the other 3rd wire.

Krone in the solid colour wire to the top connector and the striped colour wire to the bottom connector.

I had no information when I did this as to the right way round but got it right first time ;-)



4. Screw the master socket back together, taking care not to trap any wires.


Plug your phone back in if you had one here (and check it still works)!



5. Next get your standard telephone cable with an RJ11 terminator one end and telephone connector at the other.


I took mine from a spare corded phone I had in the house for power cuts.



6. Plug in the telephone end of the cable into your existing extension socket.


Connect the RJ11 end of the cable into your BT Infinity modem or BT Home Hub 5.



7. With your BT Infinity modem connected to the DSL extension socket, power it on.


The DSL light will flash while it negotiates with the BT exchange.

Once it has connected the DSL light should stay on like below.

If it does not, check your cabling and or try another socket in the house incase you picked the wrong extension wires.



8. Next connect your BT Home Hub 3/4 to the BT Infinity modem and power it on.


After a minute or so it will have booted up and the broadband light should be blue.

Check either your laptop/PC/tablet/phone to ensure the internet is working.

Job well done!



If you have the new BT Home Hub 5 you can just connect it directly with the RJ11/telephone cable to the extension socket like below. You no longer need the white modem box with fibre to the cabinet (FTTC). Which saves having another box laying around and another power socket being used!






Just an extra photo..


If you unscrew the 2nd part of the master socket (the part the BT engineer added when they installed BT Infinity) you will see the actual master socket and how all 3 parts fit together.

It also allows you to see all the cables a bit easier if you've got several extensions coming into the socket.


The only jibe I have of BT is why couldn't the engineer connect this DSL extension socket up in the first place. Everyone seems very confused and annoyed in the forums because their master socket is in an awkward place and like lots of people their ADSL broadband was in another room. This achieves the same result. Yes the internal cabling might degrade the speed somewhat, not in my case, but it also could for ADSL so what's it matter. It's copper from the cabinet so an extra few meters of copper doesn't make much difference.



Note: This article is off my normal topic and specialism of virtualisation and IT, the usual disclaimer below is still applicable. Additionally if you blow up yourself, your house or your dog I am not responsible, always seek advice from BT if you are unsure.


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All advice, installation/configuration how to guides, troubleshooting and other information on this website are provided as-is with no warranty or guarantee. Whilst the information provided is correct to the best of my knowledge, I am not reponsible for any issues that may arise using this information, and you do so at your own risk. As always before performing anything; check, double check, test and always ensure you have a backup.

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