The below image displays the incoming cable from the telephone provider. As far as I have searched it's a 5-pair telephone cable.

I was suggested by the telephone company to replace the current telephone wiring (single pair cable) with a CAT6 cable. But, I wasn't able to find any information as to how I can connect a CAT6/CAT6A cable to this 5-pair cable.

As you can see, the current telephone line uses the 2 left-most wires, and CAT6 is a 4-pair cable. So, should I use the remaining 8 wires for the CAT6?

Additionally, if anyone is aware, I would really like to understand the purpose of these 10 wires (which wire carries what signal).

P.S: I think this is the right channel for this question. But, if it isn't please suggest where it should be posted.


Thank you all for the quick response. To clarify the use-case I am adding more context.

I live in Cyprus. Our house is located in the country-side, around 15 Km from the city center. It's a VDSL line, which is directly connected to a VDSL modem. The phone gets connected to the modem and works on the VOIP protocol. All the ethernet connections are also connected to the modem.

The available internet speed in this area is 50 Mbps (yeah, it's Cyprus!), but I was getting around 25 Mbps. So, I called a technician and he said that the analog cable is the culprit and asked me to replace the phone wiring in the house with Cat6.

I am also attaching the photo displaying the connections available on the modem. The input port is a 2-pair RJ11. And, I don't know the purpose of the WAN port.

enter image description here

enter image description here

  • 1
    The usual options for "4 more pairs from the telephone company" are nothing, right now or up to 4 more analog phone lines neither of which benefit from Cat6 (.vs. Cat5e) If your phone company is offering something different than usual, you'd have to ask them about that. If using a 4 pair cable, I'd just connect the matching pairs and leave Slate disconnected, barring something unusual.
    – Ecnerwal
    Mar 8, 2021 at 23:55
  • 7
    What is your goal? Why do you need new home telephone wiring? What phones do you plan to install? What phone service are you ordering from the phone company?
    – jay613
    Mar 8, 2021 at 23:59
  • At best that will have cat3 throughput I provided a possible answer for additional wires but the internet only electricians did not like it. Almost every home built in the 70’s or before had 4 wire, some had 6. In the early days of DSL phone companies started adding more lines to the drops so 4 pair 8 wires was quite common yours has an additional pair. The telephone company used punchdown blocks 66 was the first and will still work fine with telephone today. In the 80’s they came up with with the 110 block that was compatible with cat5 wiring. I know cat5e works on 110 ? Of cat6 or higher.
    – Ed Beal
    Mar 9, 2021 at 14:18
  • I've edited the question with more information. It's just a single VDSL line, no independent phone signal. The Phone is connected to the modem and works on the VOIP protocol.
    – anemo
    Mar 9, 2021 at 15:45
  • I haven’t compared the cost of 5 and 6 lately but looking at how unwound those wires at the punchdown block are I would think a complete rewire would be needed. cat 5 with proper punchdowns will meet or exceed your dsl’s capability of 50M (5 is rated to 100M with proper connections.) this might save you as having the capability to go to GB is a waste if your provider is currently only 50 and I don’t think I remember speeds over 100. In my area the providers went to cable & RF systems but there are still dsl providers just not many compared to 20 years ago.
    – Ed Beal
    Mar 9, 2021 at 17:43

3 Answers 3


Each of the incoming pairs in the telco's 5-pair cable is for a separate analog telephone line (or, in today's world, a single DSL channel). The pairs are identified by color: there's a solid blue wire paired with a white wire with blue stripe (also called tracer); a solid orange wire paired with a white wire with orange stripe, and so on with green, brown, and gray (slate).

The drop cable includes several pairs in case a subscriber might have wanted ability to make a voice call on one line while also using a modem or fax machine on another line. Sometimes pairs "go bad" due to cable damage, water ingress in the cable, etc so the extra pairs also provide some redundancy against that possibility.

I'd connect the blue pair of the CAT6 to whichever of the telco pairs has your primary telephone line, the orange pair to the second line, and so on. If you have only one line then connect only the blue pair from the CAT6.

As for mechanically how to carry out the connection: you need a "punch down tool." These look like 110-style terminals. A professional tool is spring-loaded, trims wires to length, and does other neat things. But you can get a simple inexpensive plastic tool as well -- these are sometimes included with CAT5/CAT6/telephone "keystone" wall plate jacks. If you're careful and attentive, you could even get the wire pushed down into the terminal using a pair of small flat-blade screwdrivers.

Here are a few examples of 110 punch down tools: enter image description here enter image description here enter image description here

Interior wiring is a common source of trouble especially for DSL services. The cable shown in your photo is basic 4-conductor. Twisted pair CAT-rated cable tends to perform better. CAT6 is significantly over-qualified for the application (CAT5e, CAT5, even CAT3 would do) but it is commonly available and there's no appreciable difference in price vs the lesser cables.

The technician might also have recommended replacement for another reason: the home's existing phone wire might run all throughout the house, have many junctions that could be problematic, etc. A new cable that goes directly between the phone demarcation point outside to your DSL modem will eliminate those variables.

With possibility of trouble in your inside wiring eliminated, if the low speed persists the DSL provider may be more willing to troubleshoot their network to search for connection problems.

It's worth confirming whether your service is two-pair bonded or single-pair, and if bonded which one is the second pair. A bonded service with only one pair connected would get half the throughput.

The modem has a WAN port probably because it is designed to work with both xDSL and another service like fiber to the home. In the latter, some providers install a box called ONU/ONT (optical network unit/terminator) to convert from optical fiber to Ethernet. That Ethernet would connect to the WAN port of a gateway device like yours.

  • Only difference is I would punch in all 4 pairs, regardless of if all 4 pairs are in use (right now.) If nothing else, it's mechanically better.
    – Ecnerwal
    Mar 9, 2021 at 13:28
  • Each pair is not always for a phone line DSL requires 2 pairs and many phone companies started dropping additional pairs in their lines for data.
    – Ed Beal
    Mar 9, 2021 at 14:06
  • 1
    So, does this mean, he asked me to replace the cable only to improve the signal quality? In other words, even after installing Cat6, I will still be using only the first pair, but I will get a better signal, and thus the improved speed?
    – anemo
    Mar 9, 2021 at 15:31
  • @EdBeal It depends on the flavor of DSL (ADSL, ADSL2, VDSL, and so on). All can operate on a single pair; some support multi-pair bonding like the 2-pair version you're familiar with. Multi-pair requires support in the DSL modem and the DSLAM too.
    – Greg Hill
    Mar 9, 2021 at 15:44
  • 1
    Ed, back in the Dark Ages ® I had DSL in multiple locations (home and work.) One pair, the same pair the analog voice was on - filters to remove it before it hit the voice phones. There might be other variants that used more, but I never saw them in the wild. Heck, I have friends less than a mile away who are still in those Dark Ages ® (7mb down, 1 MB up, who-hoo!!)
    – Ecnerwal
    Mar 9, 2021 at 18:35

Edited answer, now including new details on situation: OP uses DSL only from provider, provider terminates outdoors at pictured punchdown. The modified requirement is: extend provider DSL wiring from outside punchdown to inside router which has RJ11/12 jack, with no phone service from provider.


Buy a twisted pair ethernet cable, Cat-anything, long enough to get from the outside service cable to your modem. Ideally, if you can find a one long enough, twisted pair with RJ11/12 ends (perhaps sold as a DSL cable) that would be great. But those are rare so we’ll allow for unterminated cable or for RJ45 ends if that’s the cable you have.

You may also need one surface mount wall jack (picture below). Perhaps you can scavenge one from your disused house wiring.

If your wire has RJ11/12 ends

Remove the service wire from the punchdown block and install the surface mount wall jack to the service wire. Plug your cable into that, and plug the other end into your modem. Done.

If your wire has RJ45 ends (or no ends)

At the service end: cut off the RJ45 plug if there is one, remove the service wire from the punchdown and use any terminal block, or crimp connectors, or solder, or whatever you want, to connect your new wire to the service wire. Do it neatly with as little as possible of untwisting the pairs. Make sure the pairs match to pairs. Protect this from the weather, in whatever way the existing system is protected.

At the modem end: If the cable has an RJ45 end cut it off. Then if you can crimp on a n RJ12 plug, do that. If you cannot, install the surface mount wall jack at this end of your cable and use a short, high quality telephone patch cable to plug into your modem.

Note re order of wires: Your phone service seems to be in order blue-orange-green. Those should end up in an RJ12 plug as innermost pair (blue) to outermost pair (green). You'll have to figure out, depending on exactly how you do this, how to make sure to match the wires correctly. Using a screw-terminal wall jack instead of, or before, crimping an RJ12 plug will help you if you get it wrong.

Finally: house phones

If you still use your wall jacks for phones, now that you have removed the provider service wire from your home wiring, you can use an ordinary phone patch cord to connect the VOIP socket of your modem to any existing wall jack, and then all the other wall jacks should work. More likely however, you have a portable phone system and you should plug the base station directly into the modem's VOIP port.

surface mount telephone jack with screw terminals

  • thank you for the input. When you say "disconnect from the punch-down block", how do you suggest leading the cable indoors? solder the home wiring to the telco cable? or use an RJ11 extension socket?
    – anemo
    Mar 10, 2021 at 10:27
  • Wait what? Is that punchdown block outdoors? I assumed it was indoors, you could rip the feeder cable off it, and attach directly to that in various ways. Just crimp an RJ12 directly to it, or use a terminal block, or a terminal-based RJ socket that you can then use a phone cable to your modem, or solder ... anything. In the USA we have a modular termination box outdoors or indoors, and he punchdown comes AFTER that. IF you have a termination box send a picture of all its innards. I'll make a suggestion.
    – jay613
    Mar 10, 2021 at 13:25
  • No termination box. The Telco cable is attached to the punch-down block, which is located outdoors. And, the internal wiring is directly connected to the punch-down block.
    – anemo
    Mar 10, 2021 at 14:47
  • 1
    Ok I'll edit my answer accordingly. Do you have any telephones plugged into wall jacks in your house, or just one phone (or base station) plugged into the modem ?
    – jay613
    Mar 10, 2021 at 15:01
  • 1
    Answer has been edited to reflect that service termination meets house wiring outdoors.
    – jay613
    Mar 10, 2021 at 19:04

Old school was 4-6 wires when dsl came along the needed the extra double pair. I don’t know anyone using dsl any longer but I am sure they are out there That is the most likely reason for the extras I never saw a house with less than 2 pair and many had 3 in the 80’s then dsl and today everyone has a smart phone , not everyone but you get the idea.

  • 6
    The standard for where PSTN lines are still in use is usually still one pair only connected, even if you have DSL. DSL can coexist on the same phone line with a voice call. You pay extra for the additional lines for e.g. a fax, a separate work number etc. Mar 9, 2021 at 9:02
  • You are only right in bell telephone wired almost every drop with 4 wires, I found an area in the early 80’s that had 6 wires. The 4 wires were Red, Green, Yellow & Black one pair was in use yes but I never said more were in use the cable that the phone company laid always had at least 4 wires as well as every 4 conductor connection point inside the home.
    – Ed Beal
    Mar 9, 2021 at 14:03
  • 2
    I think I see where the confusion might be coming in. Every analog phone line coming into the building - whether just voice or voice + DSL - was just a single pair. The wiring from pole to building was usually several pairs to avoid having to add another cable to add another phone line (or to replace a single bad pair). The wiring inside buildings would normally be a minimum of 2 pair, typically 3 or 4 pair, and in larger buildings 25 pair. DSL did not need a separate pair, but it was not unusual to filter & split it at the DMARC and then feed the voice off to the phone system and Mar 9, 2021 at 15:24
  • the DSL off to the server room. I would do this routinely even in an ordinary house as it avoided having to put filters on every phone (if they didn't have an actual phone system) and also avoided having to put the DSL modem + router + switch (which could be anywhere from 1 to 3 actual devices) at the DMARC because the ordinary pair (i.e., 2nd pair in a 2-or-more-pair cable) could handle DSL by itself just fine but was not (even if multiple pairs) good enough for Ethernet. Mar 9, 2021 at 15:28
  • 1
    Yup, a master splitter to separate the DSL wiring from all the reflections, tees, and poor connections left over from 50 years of phone wiring is definitely recommended for anyone still using DSL. Mar 10, 2021 at 4:45

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