I have a room (room A) with a wifi router setup, where there is an unused outlets with two vertical plug-in slots near it. My office (far from room A) has something similar (with 1 plug-in slot). I tried but the ethernet cable doesn't work. Can these be used to somehow connect my router internet to my computer in my office? If this is for TV or phone which I have no use, can I use the existing line to fishing through an ethernet cable so I can connect my computer in the office to the router physically? enter image description here enter image description here

//////////////////////////////////// Edits: Added more photos enter image description here enter image description here enter image description here

  • 1
    Will need to see if any wires/cables are connected to those outlets and find the other ends. They look like ethernet outlets, but the big question are they hooked up to anything.
    – crip659
    Commented Dec 28, 2022 at 19:47
  • I lived in this house a couple years ago. Never used it.
    – KubiK888
    Commented Dec 28, 2022 at 20:26
  • What do the words printed on the cable say?
    – user71659
    Commented Dec 29, 2022 at 6:08
  • 1
    if you are sure they are connected to each other i would pull through a utp cat 5/6 cable and replace the sockets with rj45s
    – JoSSte
    Commented Dec 29, 2022 at 11:12
  • 1
    They likely are not connected to each other. @Criggie I have been to the attic, how do I find out where these outlets are leading to?
    – KubiK888
    Commented Jan 5, 2023 at 23:05

6 Answers 6


These are phone wires. I would not bother trying to use them for ethernet. Even if the wires themselves are suitable for it, there are so many phone-wire installation practices that are incompatible with ethernet that I wouldn't count on their working properly. And "properly" is a big deal ... they may work poorly or intermittently and you'll never know, you'll blame your ISP or your laptop or you'll get slow performance and think it's normal. Not worth it.

If these wires were fished into place you can probably use them to pull new ethernet cables. If they are stapled or snaked through holes in studs and joists you'll have trouble using them for pulling and it'll probably be easier to find a new path with snaking tools.

  • Measuring the bandwidth between two devices on the same network is a surprisingly good diagnostic tool.
    – jaskij
    Commented Dec 31, 2022 at 11:23

Typical phone jacks and Ethernet jacks look the same from a distance. They are slightly different sizes and the key is the number of pins.

  • 2 - single phone line and some digital (but not VOIP) phone systems
  • 4 - two phone lines and some phone systems (analog, digital or hybrid)
  • 6 - some phone systems, some terminals from ye olden days
  • 8 - Ethernet networks, some terminals from ye olden days

As far as I can tell the upper jack of the 2-jack faceplate has 6 wires. Which will not work for Ethernet. I can't tell what the others have. But all is not lost - you may have standard 4-pair cables even if the jacks have fewer than 8 pins. If that's the case then the quality (old junk vs. Cat 3 vs. Cat 5 vs. Cat 5e) will determine whether you can make use of the cables or not.

But in addition to the number of wires, the big issue is the routing. For traditional phone service (analog voice, fax and modem) you can use a star configuration or daisy-chain. Twisted pair Ethernet networks and most phone systems require a star configuration. If you either have a cable (8-wire, preferably Cat 5 or better) going directly between the two locations you want to connect or if all the cables go to one central location then you can use the cables to set up an Ethernet network.

Based on the pictures, it looks like the wires attached to each jack are a pair from a 3-pair cable. While it is possible to run Ethernet on 2 pairs, generally speaking once twisted pair Ethernet became common the usual thing to do was to wire everything with 4-pair cable and mix/match as needed for various phone systems, Ethernet, etc. So a 3-pair cable would generally predate the Ethernet era or was used to save money, in which case it would almost certainly not be even Cat 3 quality.

You might be able to use the old cable to pull new cable. That will depend on how it was installed, which is very hard to tell from the boxes. Testing first to see if any of the wires are connected, and searching to see if they are going to a central location, are the next steps.

  • 2
    I have added some pictures behind the plates
    – KubiK888
    Commented Dec 28, 2022 at 21:51
  • 4
    You can use the holes in the wall and run new Cat5 or better cable along with all new CAT5+ ends. Using the old wire will probably never work correctly.
    – Gil
    Commented Dec 29, 2022 at 0:22
  • 2
    8 pin jacks are quite common in ISDN systems, in countries or sites where ISDN was widely deployed.... Commented Dec 29, 2022 at 22:42

These are without a doubt Telephone Jacks. The Jacks in Room A are 6-Wire, so they're RJ25, while the jacks in your office are the older 4-Wire RJ14.
That said as both jacks have RJ25 cabling the only issue here is the jack itself in the office, so you could easily upgrade it to RJ25 or even RJ45 in both rooms (Ethernet wiring uses RJ45) albeit with limited speeds.

There are networking solutions that do allow you to use Telephone jacks for your network, I used to sell PCI cards that did this in 1999! Though you can simply make one yourself using (2) RJ45 Couplers (Female > Female) and by cutting a RJ14/RJ25 phone cable in 1/2 and wiring 4 wires from each end into a RJ45 Ethernet Cable Crimp Connectors following the wiring diagram below to wire up Pins 1,2,3 & 6. As for the phone wires it doesn't mater which you use as long as they're wired the same on all ends you shouldn't have any issues. But here is information and a diagram on phone wiring.

RJ45 Wiring Diagram

10/100 Base-T cabling only requires 2 pairs (4-Wires), so if you're ok with speeds under 100Mbps, say if for example your internet speed is slower than 100Mbps, then you're not missing out other then perhaps on local traffic between other devices on your network and your Desktop in the office.

It's a shame the rooms are so far apart as a simple solution would have been to use Ethernet to Powerline adapters which would have offered decent performance, but I doubt based on the distance they will work as they need to be on the same line/breaker.

You're likely better off with Wi-Fi for speeds in excess of 100Mbps (and Wi-Fi Range Extender if you need to boost the signal coverage area).


As others have pointed out, these are phone lines.

These rooms are not connected directly to each other, so using the old phone line to pull new ethernet cable is probably not feasible. The cable from each room probably runs back to a hub where the landline phone service splits out. In older homes, there was often a single phone cable that snaked from room to room and could be tapped anywhere to add jacks. That doesn't seem to be the case here, since the cables end at the jacks.

The two-jack room is wired to provide one phone line to one of the jacks and a different phone line to the other. This was likely done to have a regular phone on one line and a modem or fax machine on the other. The extra pins are unconnected, so they probably used the 6-pin jacks because that's what they had on hand.

The single jack with the screw terminals is probably original to the home. It's wired to deliver just the primary line.

So, other than the walls having openings in Room A and B, none of the existing infrastructure helps. You'd have to run an actual network cable (e.g., Cat-5e) from one room to the other, which is likely the hard part. You can then replace the existing jacks with network jacks in each room and wire them to the new cable. That's easy.

  • Concur - OP needs to get a helper in the roof space, and try wiggling each wire to see if they're strapped/stapled in the wall. If not, it may be possible to pull new UTP wire using the phone cable as a draw-wire. Fun times ahead.
    – Criggie
    Commented Dec 30, 2022 at 2:26

These are phone plugs, but the wire used seems to be standard RJ45 CAT5 cable (though I don't see a brown pair, it's hard to tell from the pictures). You should check the markings on the cable, and if they are indeed CAT5, then they could in theory run 100Mbps Ethernet and perhaps 1Gbps for limited distances.

So you would require new wall sockets and rewiring according to the standards, and it could all be for nothing, because the connection might be unreliable. A proper Gigabit connection would need all four pairs to be wired (8 strands) and absolutely no splicing / derivation, there needs to be a single continuous cable from the router socket to the room.

Depending on your budget, property title, type of walls etc. you need to decide if repurposing these wires makes sense and is worth the risk. For example for me, living in a brick house with plastered walls, I would definitely wire them up because the alternative is to install visible wires or turn the whole house into a construction site, ruble and dust everywhere.

  • 2
    What makes you think the cable is Cat5? We can't see any markings, so it's probably much more likely that the cable is no better than Cat3, unless the original installer wanted to future-proof and install the more expensive Cat5 (which is otherwise a complete overkill for phone of any sort).
    – TooTea
    Commented Dec 29, 2022 at 19:17
  • I can only see three pairs in any photo, there is no fourth pair required for gigabit speeds. It might work at 100 Mbit, but might not. The cost of trying is just time, and a pair of jacks and a punchdown tool.
    – Criggie
    Commented Dec 30, 2022 at 2:25

While it doesn't look like "normal" Cat5(e)/6, you can still try it. 4 wires for 100 Mbps, 8 for Gigabit. Not sure if you have 8 though, unclear based on the images.

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