I have a (UK) telephone socket in the same corner of each of the three floors in my house. My broadband router is connected to the socket on the bottom floor. The wiring looks like the following:

Top floor: enter image description here

Middle floor: enter image description here

Bottom floor: enter image description here enter image description here

What type of cable is it? Can I use it for ethernet? If not, would it be pretty straightforward to run an ethernet cable alongside it?

  • 4
    Can you unscrew the box from the wall, and pull some of the slack cable out? The writing on the side will tell you exactly what cable it is. Also count the number of wires (or number of pairs) in the cable - I see 6 wire/3 pair.
    – Criggie
    Commented Aug 19, 2019 at 0:33
  • You're in the UK - are you permitted to change the house phone wiring now? I know in the bad old days you could not change internal phone wiring, only BT could do that.
    – Criggie
    Commented Aug 19, 2019 at 0:34
  • 6
    @Criggie on a modern BT domestic installation, there will be a single NTE5 socket somewhere (not the same as the OP's "master socket 5C" pictures). NTE = "Network termination equipment." That is the point where BT responsibility for the wiring ends. The NTE socket provides a clean way to disconnect the rest of the wiring, and a test point for BT, by removing the front panel (fixed by screws) which internally plugs into the termination of the BT wiring. With the front removed, there is a standard phone socket inside which can be used to check if faults are in the house wiring or the BT network.
    – alephzero
    Commented Aug 19, 2019 at 1:11
  • 2
    ... i.e. if you take the front panel off the NTE5, plug a phone into the internal socket, and it works, there is "nothing wrong with the BT wiring" and you are on your own for fixing other problems.
    – alephzero
    Commented Aug 19, 2019 at 1:27

3 Answers 3


Gigabit Ethernet

If you need Gigabit Ethernet (1000Base-T), you're out of luck and will have to run new wires with CAT 5e or better cabling. It's likely not that difficult depending on your house. It seems like these jacks are above each other in the same place on each floor. Thus, you could easily drop a cable down from the upper floor and run them all down to your bottom floor. If the cables are in different spots, it'll be more challenging. However, you could just cut a small hole in your wall and then you'll need to cut another small hole in your frame using a bit like this. It's not as bad as it seems - especially if there's already a wire you follow (ie: your telephone line).

Fast Ethernet (100 Mb/s)

If you're only interested in Fast Ethernet (100Base-TX, ubiquitous), you can rewire those telephone lines to become ethernet lines without much work, provided the existing cables are CAT 5 or better. Check the outer sheath of the cable to determine what you have. If it is only CAT 3 then you are out of luck. You'll have to make a few concessions for that to work:

  • You'll have to have a switch on your middle floor
  • You're giving up your telephone lines (as they will be ethernet instead

The telephone wires in your house have 3 twisted pairs. Ethernet is usually ran with 4 twisted pair wires. However, for 100Base-TX, 2 of those twisted pair wires aren't used as only the orange and green are used for transmit and receive. The blue wires are used for Power Over Ethernet. From your pictures, you should be able to wire a RJ-45 Keystone Jack with all 3 pairs of your wire.

Cat5e Wiring Diagram

Basically, you'll need to take your orange, green, and blue wires and connect them to the terminal on your RJ-45 jack on each floor. On the middle floor, where you have 2 wires, you'll need 2 keystone jacks. Then, you'll need to put an ethernet switch in the middle floor and connect both the top and bottom floor (along with the middle floor). If you're only interested in connected the top and bottom floor, you can put in a small 6" patch cable to connect the top and bottom floors together. Obviously, you'll need to remove your telephone jacks to replace them with the RJ45 keystone jacks mentioned previously. While this solution isn't the fastest, it take minimum effort to get up and running.

  • 1
    Stellar answer, thanks @technogeek1995. The wires in the middle floor seem to be connected together on the plate, can I just leave them as they are (to achieve Base100T connection bottom to top, skipping middle)?
    – gozzilli
    Commented Aug 18, 2019 at 21:25
  • 2
    "If you need to Base1000T, you're out of luck and will have to run new wires with CAT6 cabling." - CAT5 is adequate for 1000BASE-T, so if the existing wiring is 4-pair / 8-wire CAT5 (doesn't look like it though), he doesn't need to replace it.
    – marcelm
    Commented Aug 18, 2019 at 21:31
  • 5
    They don’t need to be foiled or shielded at it’s a digital transmission. Being twisted pairs is the most critical to prevent interference, but I can’t tell from the pictures. However, judging by the cable, I don’t think it’s likely they aren’t twisted pairs. Even 4 wire phone lines should be twisted pair. Commented Aug 18, 2019 at 23:20
  • 4
    "you'll need to cut another small hole in your frame" - this is the UK. If this is an outside wall, it is almost certainly a brick or block wall, not a wood frame. Commented Aug 19, 2019 at 8:46
  • 2
    Cat3 (often used in in-house ISDN lines) is usually enough for 100baseTX. The OP doesn’t need to wire up all three line pairs, just two of them, but the how is important (to keep the pairs twisted inside the cable matching the connector pins correctly).
    – mirabilos
    Commented Aug 19, 2019 at 17:19

The cable type is almost certainly BT spec CW1308, 3 pairs would be normal for UK extension wiring.

It won't be to Cat5 or better spec, but over a short run and without external interference you will probably get 10Mbits over it, maybe even 100Mbits.

  • 3
    Cat3 (or similar) for 100 MB is often a big problem. If you can force it to 10 MB then it is great - and plenty fast enough for a lot of uses. But if you can't force it to 10 MB then it might bounce between 10 & 100 or run at 100 but with a lot of errors which can slow things down to worse than 10 MB. Easy fix would be a 10 MB switch in the middle location - if you can find one. Commented Aug 18, 2019 at 19:15
  • 4
    @manassehkatz If the network card can do 10 Mbit/s in the first place, then there's usually a way to set it via software to force it to use only 10 Mbit/s, rather than to autosense the speed. Beware, both ends have to have the same setting or it won't work.
    – user
    Commented Aug 18, 2019 at 19:46
  • 2
    CW1308 is basically CAT3, and CAT3 is sufficient for 10BASET, so you should indeed be able to get 10MBps over it, even over relatively long runs :)
    – psmears
    Commented Aug 19, 2019 at 12:56

I would inspect to see if the telephone cable is run in some type of conduit, but in UK that, sadly, is not always the case.

If you are lucky and it is in a conduit then I would use a cable puller and run cat 6 cable up to each floor.

If you are not lucky, then you could take the risk of disconnecting the telephone cable and using that to pull through two lines. One to put back the telephone cable and one to pull the cat 6 through.

  • 1
    ...or, presumably, just pull the cat6 through and recycle the old phone cable. There's really not much use for it nowadays. Commented Aug 19, 2019 at 19:28
  • 3
    If you want to keep the phone line without pulling up a second wire, tie a long string to the top end of the cat 6 before you pull it through. Later, you can untie it, tie it to the end of the phone cable, and use it to pull the phone cable back down through the wall where it originally was.
    – bta
    Commented Aug 19, 2019 at 20:51

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