phone wiring repair

Phone Wiring Repair and Connectors – Some Tips From A Telephone Engineer.

Because telephone wires (the ones that connect your phones to the master socket in your house) are so small, people don’t seem to take phone wiring repair very seriously, with the result that people struggle to make even the most embarrassingly messy and unreliable connections.

However, there are some easy steps to follow, using easily-available equipment, that can make phone wiring repair easier. It isn’t that hard with the right stuff.

I encounter faults from bad phone wiring repair very often. It keeps me in business. But here are some “trade tips”;-

First, The Bad News – What Doesn’t Work…

Twist and Tape. Nope. This results in the cables eventually snapping, and to cover the taped joints involves a bandage of tape the size of a child’s little finger. Far too bulky. Then the tape dries out and falls off…

Mains Wiring Block Terminals? The plastic things with screw tops. Either they are too big, and don’t grip the cable, or too small and too fiddly to fit. They are nowhere near as quick and effective as “punch-down” connectors. And they look ghastly.

Car-Type Bullet Connectors. Actually, BT used to use something very similar to these, but they still need to be of good quality and have the correct tool to work well. And be crimped up correctly. Possible but not advisable. There are better ways to effecive phone wiring repair

Solder. Well, if you have the patience… But you still have to insulate the joint with something.

So, I’ve seen almost all of these type of phone wiring repair fail. Or, even worse, when you come to work on them, putting them right takes a long, long time, and the customer thinks you’re from “Mr Bean Telecom” because you are taking so long over one tiny joint or box. If only they knew…

Now, The Good News – What works?

An “in-line connector block” (“BT 78A”) like this:-

They use the same connectors as a typical phone socket, that is of the “punch-down” type. This pushes the cable into a sharp metal “V”, strips the insulation (and holds the wire firmly in place at the same time), and makes positive electrical contact. You need to use a special tool to do this. A screwdriver, or anything else will bend the prongs of the “V”, and render the connector useless. They are commonly available on Amazon, eBay, Maplin or similar, often known under their BT part code “BT 78A”

What else works?

Well, if you have somewhere to hide them, jelly-filled Scotch crimps (sounds like something from a Burns Night Supper…) are ideal. For a professional telephone engineer, they are an absolute phone wiring repair “life-saver”. If your DIY customer has cut cable too short in a socket, they can be used as a very quick and compact way of extending a wire. Again, these are available on-line. They work on a similar principle to the BT 78A (above), except you simply poke the wires all the way in, then squeeze with some pliers, or a special tool. That’s it! BT street cabinets are full of them. I love them!

They can be hidden inside things, such as sockets, trunking, conduit. They can also be used to connect things back together very quickly in order to get phone/internet working while you think of a longer-term fix.

And something else… 

The obvious fix. You might want to carry out phone wiring repair by actually replacing a run of cable between, say, a BT master socket and an extension socket. It’s actually often quicker to replace a full run of cable than mess around jointing in highly visible/vulnerable places.

And a quick note regarding your master socket. If you plan to move it (illegally), use one of the “bodge” methods, and Openreach come to your house and spot it, then they are likely to charge you in order to put it right, and for the trouble of coming to your house to fix a fault that (technically) you have created on their network.

If you are going to do this (and of course you shouldn’t), then at least use some professional-standard connectors. Anything else just screams “DIY”. And will fail.

There’s not a great mystery to phone wiring repair – it’s not hard to find the proper components, do it right, keep yourself connected, and telephone engineers like me away from your door.

Help is At Hand

But if you do get stuck, and you’re not far from me, that is close to Middlesbrough, Stockton on Tees, Darlington, Co. Durham and North Yorkshire,  drop me a line!. Plus, I’m in touch with many engineers across the UK.

  1. Farina11-03-2016

    This is great, would you recommend this solution for outside? We’ve cut our outside cable in 2 places so would we require two boxes? I think replacing the full length of wire maybe to fiddly/costly. Many thanks.

    • Rob Govier11-03-2016

      Thanks for the kind words. External cable is normally much more robust, and typically has a black sheath. Look for “Dropwire 10” on eBay. It can be bought by the metre. Look also for “3M Telephone & Data Cable Joint External Dropwire Closure Repair Kit”. Both these items are used by BT Openreach, and are extremely robust. Dropwire 10 demands particular care in stripping, as it contains supporting wires which are very sharp when cut. BT Openreach issue a special tool and end-protectors for handling it. But it is worth the trouble.

      I will soon be blogging on the whole issue of external cabling, so stay tuned! Rob

  2. Loftos01-02-2017


    Thank you very much. My neighbour has issues with noise on his line. and slow download speed. We share an 8 pair overhead cable, the pair to my house is fine. BT have checked his line from junction box 0.3 miles away, down the overhead cable and then the section of cable that goes underground and cannot find a problem.

    I have suggested cycling through the other spare 6 paris of wires to see if the signal improves or my other thought is combining cables, i.e using 2 wires combined together to effectively form a thicker wire with lower resistance which should improve the cable/signal.

    So my question is in a low voltage system, in theory for a 8 pair cable if you used 4 wires combined to form one half of the pair and the remaining 4 wires to form the other half of the pair would this cause an issue as resistance would go down and if voltage constant then current would increase, how would this effect the system/signal?



    • Rob Govier01-02-2017

      Ben, This fault really is in the realm of Openreach and should be kicked back to them. Any “fix” involving bonding legs of a cable is utterly up to them. But if the noise is on one of the legs bonded, then the noise will persist, and nothing will be gained. Noise can often be caused by water ingress to damaged cable or joints. Does the issue get worse in damp/rainy weather? With all line noise issues, I always try and call the customer services call centre from the line with the noise, get the agent to hear the noise for themselves, and insist that this is documented on the ticket. Just for your information, dialling 17070 from the affected line and choosing the “quiet line test” from the menu will make the noise more audible. I end where I started – this one most certainly needs to be pursued with Openreach. Rob.

  3. Bill J03-08-2017

    What a great post – thank you. Like others, I have a noisy line. Being nosy, I can see that there has been water ingress (copper staining) into the Scotch crimps outside my house where the Openreach cable is joined to another short cable that goes inside to the socket. My master socket is actually in another room, and Openreach did this move when they installed Infinity. So my old ‘master’ socket just contains another set of Scotch connected cables. The right thing to do is to convince BT (supplier) to call out an Openreach engineer, obviously. Or I could get me some Scotch crimps 😉 Have you seen Openreach use anything to weatherproof the connection when outdoors? The grey cable cover doesn’t keep out moisture or creepy-crawlies.


    • Rob Govier03-09-2017

      Thanks for your kind words!

      If the Scotch crimps are in good condition and applied correctly, they should be fine for installation in a grey external box (Google “BT66B” to see if this is the one you mean).

      They are jelly-filled, and when squeezed to terminate the wires, the jelly oozes out to protect the joint. BT/Openreach use them all the time in semi-weatherproof situations, such as their street cabinets,up poles and down in holes, which are out of direct rainfall, but can be susceptible to damp.

      The fact that you can see the classic green copper staining means that moisture is degrading the cable core. As well as causing the “distant crisp packet”-type rustling line noise, this also slows down broadband. I have known of a marked increase in speed occuring simply by retermination of some incoming cables in a property which showed no outward signs of corrosion.

      The choice is yours:- you can either report it to Openreach (“OR”) via your provider, and they will threaten you with a £160.00-plus bill if the problem is your side (which it probably isn’t). This is after you’ve spent time queuing at a call centre. You then have to be around for the OR person to turn up at your premises. And then correctly diagnose and fix.

      Alternatively, you could buy some Scotch crimps from eBay and reterminate the joint yourself in 5 minutes. (Not that we’d ever officially recommend interfering with their side of the network, of course…. 😉 )

      Tools required would be a pair of cutters and pliers. Cut each cable back to clean copper, insert each as far into the crimp as possible, and squeeze. Jelly should ooze from each channel of the crimp.

      On the other hand, if you do call your provider, make sure you call them from the faulty line when it’s noisy (often in damp weather conditions). Then the call centre operative can hear the noise themselves, and might actually just believe you.

      One professional secret:- If you call 17070 and select the “quiet line” option from the menu, you’ll be able to hear the sound of silence, proving that the noise has gone. But please note, some providers have inhibited use of this useful, age-old service.

      I hope that this helps, and you get the fault cleared!

      And now my standard request for a favour:-

      If this information has been helpful, would you consider leaving some feedback on one or all of the following, please? It helps me to continue to provide free advice, and find local engineers!

      • Neil Beaton03-16-2017

        Cracking advice, and always very helpful to hear from a professional chap. I was just gonna ask you, how do you remove already fixed cables in an OR box. Do you cut them with side cutters or use the punch down tool. Cheers.

        • Rob Govier03-16-2017

          Thanks for your kind words! If they are punched down in “Krone” connectors, then you’ll need to gently pull them out. Cheaper, flimsy boxes can often be pulled apart this way, so take care. It i spossible to pull the connector block off the back board of a socket and sever the solder tracks.

          Removing the old cable allows new cable cores to be inserted. Usually they will accommodate two in the same prong – but only if they have space in the first place!

          Professional-grade punch-down tools have an integral fold-out hook that does the job very well. It also rips skin…

          I hope that this helps!


          If this information has been helpful, would you consider leaving some feedback on one or all of the following, please? It helps me to continue to provide free advice, and find local engineers!

  4. Sam04-12-2017

    Hi Rob, thanks for a great article. I work from home so use a BT business internet connection throughout the day. Only problem is the connection drops for a second every time anyone opens the front door of the house, which is next to the Openreach box. This is enough to throw me off calls altogether and I have to restart.

    I have had BT engineers over twice. First they diagnosed a faulty plug on the router, we changed that but the problem continued. Then they diagnosed a faulty router, again we changed but it did not sort the problem. I think the wiring is faulty/loose and opening the door is causing the connection to drop, but whose responsibility is this and how can I get it resolved?

    Many thanks, Sam

    • Rob Govier04-24-2017

      Sam, Sorry for the delayed response – I can’t recall if I replied or not!

      Thanks for your kind comments.

      The intermittent fault sounds like it’s Openreach’s side, but they may quibble if they come and see you, and suggest that you have damaged their cable. They may then try and charge you £130-£160 for the remedial work. It very much depends who you get, though. Some engineers respond better to the pressure to get jobs done imposed on them, and are willing to spend time with customers to sort things out at no cost. Others are less helpful.

      I’d suggest getting an independent engineer to take a look. Let me have your postcode, and I’ll check who is closest to you. Obviously there’s a charge, but dealing with your supplier’s customer service desk may drive you to self-harm. You may also get a faster response. Ron

  5. Sarah04-15-2017

    Thanks for the information! I’ve accidentally damaged my phone line (before the master socket) so planning to repair it myself to save the cost of calling out an engineer.

    I just have one question that I’m a bit uncertain of. Where the telephone line comes into my property there’s a junction box where the wires are connected together. It looks though that there’s 2 external wires connecting to the same internal phone line which has confused me.

    I’ll of course be connecting it back up exactly as it’s already connected but I’m just puzzled about why there would be 2 different phone lines coming into the property and connected up to the same internal wiring (I’d assumed if one of them was e.g. virgin media and the other BT then they’d have separate internal wiring)

    • Rob Govier04-15-2017


      There are usually two pairs of wires to a property. Normally, only one pair is connected, the other lying in the external junction box disconnected. They are usually orange and white (first pair used) then green and black (second pair for an additional line).

      I’m as baffled as you! Maybe someone has fiddled with it in the past, and has connected everything “just to be sure”. I often see similar bodges.



      • Sarah04-15-2017

        Thanks for your reply 🙂

        I had a closer look at it and there’s 4 wires in the internal line, and then there’s 2 external lines, each with 4 wires, but there’s 2 wires from each of the external lines connected up to the internal wiring, while the other 2 wires on each of the external lines aren’t connected at all. It’s really strange, but I’ll just put it back exactly as it is so I don’t cause any problems.

        • Rob Govier04-15-2017

          My background is business-to-business telephone engineering work. Most of my industry colleagues won’t touch residential work because of “surprises”like this. It takes time to sort out how someone has varied from a standard configuration even before remedial work starts!

  6. chris durham04-16-2017

    Hi, I’m pulling carpets up in the bedroom and decide to cut through the wires of a BT80B box hanging from the skirting thinking it was dead. I now have no phone line.

    Can you advise?
    Thank Chris

    • Rob Govier04-16-2017

      Umm.. check which colour of wires serve your formerly live socket. Then reconnect what you’ve disconnected. Check for a dial tone. Lots of this stuff is calm and sequential checking.

      If you are struggling, I may be able to find engineers in your postcode area.

  7. Victor Franklin04-18-2017

    I cut a really old cable has 4 wires 2 orange and 2 blue all with different stripes and markings ihe. Black coax was oily inside we are in Mi mostly sand nothing stays buried too long could this be from the old cable company that came and left this 200 population years ago ? 4 wires what is this ?
    Thankyou !

    • Rob Govier04-18-2017

      Are you in the US? We are in the UK, so won’t recognise your types of cable. Sorry!

  8. Mr Mac04-26-2017

    Great tips here thank you but no meation of keeping the pairs twisted, vital for a data service. Data just like us will slow down when the interference increases!

    • Rob Govier04-26-2017

      Thanks for the comment. A good point! However, I try and keep things as simple as possible for readers, many of whom are keen DIY-ers with no background in comms. Maintaining a twist inside the confines of an LJU, module or connector may be slightly too much for some.

  9. Emma Westcott06-17-2017

    Hi and thank you for your write up! I’m in a bit of a pickle as the house I bought only has one phone box in the upstairs bedroom (the black cable from outside runs into this room. The room is my toddlers bedroom and he has pulled the black wire out of the box and now we have no Internet! Can I rewire this safely as there is slack in the wire that would allow for a portion to be removed and reattached and is there any step by step guide on how to do it? Any advice you can give would be greatly appreciated as I have a 6 year old who loves a bit of netflix and cannot get online now 🙁

    • Rob Govier06-18-2017

      Thanks for the comment. It’s hard to diagnose the problem and advise on a repair without seeing the job.

      It is likely that the wires have popped off the terminals in the socket. Have you taken it apart to check?

      You are welcome to email me directly, and I could even suggest a local engineer if I had your postcode.


  10. John B06-28-2017

    Hi Rob,

    I’m in the process of connecting a pre-run extension to the master socket in my new build home. I bought a punch down tool and opened up the master socket but found that the electrician who ran the extension damaged the fine coloured wires when he stripped the outer insulation back (looks like he just ran a Stanley knife around it to strip it, pretty rough).

    Unfortunately there’s no slack or excess so I can’t just trim the cable back re-strip it further up. Most of the inner wires are damaged with a small cut in them (the copper is slightly exposed). If I were to go ahead and connect the extension will these small cuts ‘upstream’ greatly affect/compromise the integrity of the cable? I will be connecting a broadband router to this extension (can’t connect it to the master, unfortunately). I’m worried about line speed and stability possibly being affected.


    • Rob Govier06-28-2017


      Short version:- it’s always best to run new cable if the outer sheath and/or the insulation on the cores is damaged. You might get away with it, but the fault will be irritating and probably intermittent

      I would recommend jointing the cable with a Box 78A somewhere convenient, and running in a new cable.

  11. Adrian Glen08-06-2017

    Hi Rob. Our broadband keeps dropping out and have tried most fixes, like changing the router and upgrading to BT Infinity, changing filter between socket & router – all to no avail. On investigation, I notice that the alarm engineer had spliced in to the black (master) cable before the master socket and joined the alarm coax to it with jelly joints. Could this be the issue and if so, what is the fix? Thanks, Adrian

    • Rob Govier08-07-2017


      Thanks for the contact.

      Has the alarm been installed recently,and/or do you have a maintenance contract with the installing company?

      If so, I’d suggest getting them in remove their cable and come up with another solution. If Openreach came to check your line they wouldprobably charge for the call-out, as equipment has been tee-d into “their” side of the line.

      Removing the alarm-side would allow you, by the process of elimination, to see if this is the source of the problem. However,thismay invalidate your home insurance if this stipulates an alarm with a fixed telephone connection.

      Is there a set time-interval to the problem? Their equipment may have a regular “phone home” routine which is causing the disruption.


  12. Jemma02-13-2018

    Hi Rob,

    I hav a bt phone socket with two holes, one of top of the other. The top one which is for the phone has the plastic bit stuck in it minus the wire. Any suggestion how to get it out? Was considering some needle now pliers to try it. Failing hat would I be charged if an engineer had to come out and replace it when connecting a new line or transferring one?

    • Rob Govier02-13-2018

      Thanks for the question. As ever, it’s hard to diagnose this without seeing it. An Openreach engineer attending your property would charge. I would recommend using an independent engineer. Drop me your postcode via info@ and I’ll try and see who is close. Rob.

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