Picture of Hack your House: Run both ethernet and phone over existing Cat-5 cable
The new fad when building a house is to run Cat-5 cable to every wall jack. These jacks can then be used for either ethernet or phone. When we got our new house built, we chose to get four of these jacks, and we intended to use them for phone service. Unfortunately, the wifi is a bit flaky in places (even with two access points.) This got annoying up until the point where three of the four wall jacks were being used for ethernet, leaving just one for phone. This was a problem.

The solution is to run both ethernet and phone over the same existing cat-5 cable. Every wall jack becomes two jacks, one RJ-11 for phone and one RJ-45 for ethernet. This neat hack could save you a lot of money, as you only have to buy new wall plates and jacks rather than wall plates, jacks, and hundreds of feet of wire.

See how this works in the next step.

Disclaimer: I'm not sure if this is legal. The telephone company won't be pleased if you short your telephone wires together. However, if you do everything right, they won't care. Don't blame me if you shock yourself (unlikely), damage Ethernet devices (also unlikely), damage phones (not as unlikely), damage your house wiring (not too unlikely), or damage your fingers with knives (rather likely).
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mickeyaaaa2 months ago

thanks, quick search and your article means we can still use the fax machine in wifes office....for the 1 fax we might send every year or so....

KenM47 months ago

Thank you for the post, this is great. I have just one question to fully understand this. My home is wired similar to yours but it's only using the two phone wires now, the other 6 are unused. I understand how to hook up the output jacks.

My question is how to wire back to the router. Can the wires be merged together and connected to one RJ-45 and plugged into the router or does every wire have to have it's own RJ-45 jack and port space in the router router? I'm just trying to go one-way out from the router. The attached picture shows how my electricians initially used one source cable and split it into 5 or 6 cables that run throughout the house. Do I need to pull those connections apart or just put an RJ-45 on the unused wires in the source cable? Thank you!!

Octataral9 months ago

Actually as long as you are only wanting phone service, it doesn't matter if you get the red and the green (tip and the ring) mixed up. It's just a circuit. But if you're running ADSL or some other device, like those systems that help people dial an emergency number from a bracelet or necklace, then it does matter. :)

Its not a matter of life or death, but matching green/red with white/blue, etc does matter. One is tip and one is ring and if it is wrong you will have incorrect polarity which can affect some phone devices. I only know this because Im a phone technician ;)
MarcoManG61 year ago

Good info, right now I am also sharing my Cat5e for both phone and internet. I understand I cannot run Gigabit Ethernet because of of this. I just upgraded to 500mb service and the question I have is will this affect the speed. I am currently using only one twisted pair for the phone line? Thanks

Keep in mind this will work for 10baseT and 100baseT but in no way compatible with Gigabit Ethernet.
simdude2u2 years ago
But you can't run gigabit ethernet!! because gigabit ethernet uses all 4 pairs of wires.
Stonie3 years ago
Hey nice post!

Lots of good information in the comments too ;)

One question: Given that the phone line is 'live' is there any problem soldering it? with an iron that is earthed?

I have 3 Irons, one is an ESD safe station, second a Goot 12watt and a el cheapo 25watt, all three have an earth pin on their wall plugs?

I guess earthing the live wire is not ideal?

Stonie Stonie3 years ago
To answer my own question… I checked with some line techs and apparently MDFs are soldiered live. So earthing via your iron is ok… Also shorting the line (closing the circuit) probably is not a big deal either… at least not in Australia.
You might not know that you can plug RJ11 plugs into RJ45 sockets, it's specifically designed like this. So your 2nd socket could be an RJ45, this could be a bonus depending on how easy it is for you to find RJ11 sockets.

Only downside to this is someone trying to plug a computer etc into it.

Ideally should have double cable runs to every panel in a house anyway, and then patch as you need. It's nice to see some places are being cabled like this now - but then seeing single runs makes me die inside ;)
bshad743 years ago
This is very good article. Thanks. My question is that;

I have no phone at home but have DSL throgh ATT (they call it Dry Loop).

I have my Wireless modem in the home office and connected to phone jack (which is Cat5) in that room and wireless is use around the house (which is wired with cat5 all across).

I would like to use the other jacks in the house as Ethernet outlet to connect my TV media drive to avoid WiFi slowness. they are connected through wifi. How do I connect my cat5 phone jacks to my modem while continue to receive dsl connection?

How do I do that?
T3Hprogrammer (author)  bshad743 years ago
First, you should move your DSL modem into the Cat-5 junction box, which is hopefully the same place that your DSL comes in. Then, you can rearrange the cables so that the DSL goes straight into the modem, and the modem's ethernet goes into the wires that lead to the rest of your house.

If your DSL comes in nowhere near your junction box, and is for some reason wired up to one specific jack, then you will need to somehow get an ethernet line between the DSL modem and the junction box. There, you can place an ethernet switch and plug all of the pre-existing wires into it.
festec3 years ago
Lots of all new million $ homes in Calgary only have one cat5e installed for telephone and no data jack? That's not a problem for Contact Direct Connect but apparently it is a problem for the other Contractors they need two cat5 cables for the same level of function at twice the cost..
Data networking, which should be an inherent capability of a well-designed phone cabling system, its completely unsupported by the common "hard-wired" design. If data networking is done, separate 4-pair cables are run to a modular patch panel. The problem with this is that now some wall jacks are just for voice and others are just for data. Each jack is less powerful because of its specialized use. Total system cost must be much higher for a given level of functionality. The system will work, but is neither structured, nor optimal.
lperkins3 years ago
Rather than hack apart your wires in the wall, you can buy or build what's known as a "splitter." You put one on each end of the wire. They're easily available to split the cable into two ethernet channels, or four phone channels. Making a custom one is as easy as doing what you did here with a short piece of cable and putting a plug on the end of it. Keep the wires as close to their original configuration as possible to minimise the amount of interference you pick up. (Read don't untwist the wires any more than absolutely necessary, and have them fork off from each other at the last possible moment.)

The advantage to doing it this way is that it's not permanent so you can reconfigure your panel any which way you want in the future.

I can probably be convinced to post an instructable about making splitters if anybody's interested.
goodmike5 years ago
There seems to be some basic misunderstanding about how the telephone company gets from its central switching office to your house. First of all, almost all single line, residence phone lines come into your house on one pair of wires. If you have DSL in addition to local phone service, you still only have one pair of wires (identified as "tip" and "ring"). Both voice and data have distance limitations when transmitted over wire...enter fibre optics. The phone companies use fibre optics to overcome the distance and bandwidth limitations of metallic conductors. In my area, something called a DSLM (commonly referred to as a D-Slam) is used to carry voice and data signals great distances from the central office to your neighborhood. You have probably seen repairmen working at a green metal box about 5 feet high, 3 feet deep and up to 15 feet long. That is the DSLM terminal that server the neighborhood. It is fibre optic from the central office to the DSLM, then one metallic pair to the individual house. One DSLM can serve 24 or 48 or 72 or more individual homes. However, at the beginning (the central office) and at the end (your house) you still have one pair of wires.

By the way.  My knowledge comes from a 40 year career with BELLSouth in Florida and North Carolina. 
A DSLM or a Remote Concentrator Unit (RCU) make it possible to provide ADSL service to customers who are tens of miles from the central office, where ADSL is usually limited to 18,000 feet.
Groxx5 years ago
I quite like this setup, though I would miss my gigabit connections for remote backups. And I feel compelled to say that while I like the red/green labeling "for the benefit of the color blind", I must ask... If they're color-blind, how will they tell red/green when actually doing this? (..though while typing that I realized that, if they kept a red light handy, they could tell the red one by the one that gets lighter when lit by red.)
 Groxx - you should be ashamed! Treating the disadvantaged as though ONLY the people who see color and color code items!


We actually can compare shades - and if you put green and red side by side you see a difference in shading. But there is no red or green. And we learn tricks too about using striped wires as guides and just generally in worst case scenarios just make sure the "shades" all line up. Just an FYI from a 20 year vet of the tech-age. You should see me with resistors!

I had a cable tech that was color blind.

He ran circles around the guys that could see colors.

His terminations were better then the non disadvantaged guys.

Now I did not know that he was color blind and once I found out I was truly amazed.

There are a lot of people out there that are handicapped and can overcome the disability and you would never know it.

Personally I try to contract persons with disabilities most of them work better then someone with out a disability.
pcooper2 cowen4 years ago
Most men with color blindness are red/green color blind, meaning that they can't distinguish red from green. They can see other colors, though.
SMD ones have the value printed on. just sayin'
It doesn't matter if your color blind and mix up red and green because they aren't polarity sensitive.
Until you update to digital which is polarity sensitive in most cases.

Manufactures are making Data equipment IDIOT proof so that all that is needed is to run a cable and punch the "wires" down in the slots at both ends with out making sure it is right.

The ports will align themselves to the right pin outs regardless of the (fancy term) Wiremap.

Wiremap is a method to see what wire is to what pin.

Orange pair
Green pair
Data pins

Blue pair
Brown pair
Future use and or grounding for EMI interference.

Structured Cable comes to mind.  The cable in a whole provides the stability and the green and orange are twisted more then the blue and brown pairs are.  Cat6 has even more done with it.  I will not go into a whole explanation of what mathematical science is used to create the cables twisting just know there is.

This basically has to do with magnetism.  These pairs are twisted together in counter twisting rotations. If you have two magnets a North magnet and South magnet they repel each others force.  That is what is going on inside the cable.  That is why the cable has 4 pairs that are lined up the way they are and why each pair is twisted together in better grade cable there is a plastic separator between the pairs(cat6 typically).  Splitting out pairs destroys this entire design.

Running  cables close to EMI (transformers and such is bad too) is reduced by this design but deliberate placement should be used.

The center pins are reserved for line one teleco but it depends on what you are plugging in.  That is where the codes/standards/practices come into place.

EIA/TIA established this years ago (1980s) and we technicians follow these today (2010- and forward) so that one cable can be used with any configuration with out having to tear it up and figure out what the person was thinking that connected the jacks and plugs in the first place.

We follow a strict 568B straight through pattern for a reason.  Specialty cables are heavily marked as such.  The inexperienced just slap it together and hope it works and disclaimer that it if does not they are not responsible for damages.
shtihl5 years ago
if you wanted to avoid soldering, you could pick up a set of Telephone Wire Splice Connectors which are located in the same section of the big box hardware store (starts with HD) as the other parts you will buy for this DIY. they are red and allow you to crimp two wires into one by simply squeezing the splicer with a pair of pliers or the needlenose on your multi-tool
cowen shtihl5 years ago
You CAN NOT use this on DATA. To use this on a data cable these untwist the cable. From the above discussion about the need for twisting of the pairs these splices are designed not to work. It is not IF you will have a failure it is when.
pcooper2 cowen4 years ago
You CAN use these crimp splices on DATA. Make sure the pigtails are kept as short as practical. The pigtails are an impedance discontinuity in the cable, but as long as one has very few of them and the size of the discontinuity is kept small, most systems have enough tolerance in them to still be able to work reliably.
T3Hprogrammer (author)  cowen5 years ago
The method described in the instructable does not modify the twisted nature of the ethernet wires (I was very careful about that.) Be sure that if you use another method (such as these splices) that you leave the data wires twisted up until 1/2" from each termination.
I don't know how different are your phone landlines from the ones in Brasil, but what I've noticed is my phone will work regardless of the polarity of the wires. As long as I connect both, the phone works.
Polarity does matter.
Most phone have polarity correction built in and hence you won't notice any difference on your phone, but your modem and adsl signals will suffer with reverse polarity.

Phone lines are 48VDC on idle, 90VAC on ring and around 30VAC when in use.

you can check with a multimeter but red should be negative (odd but true) and green should be positive.

If you have a second phone line, black is positive and yellow is negative.
Phone lines are -48 VDC open circuit. The ring signal is 30-34 VRMS superimposed on the DC, so the swing is roughly between ground and -96 volts.

The old 4-conductor, beige jacketed household telephone cables typically used red and green conductors for the first pair, although this is not true of CAT-5A cable which uses eight white wires with various color stripes. Wire pairs are twisted together in CAT-5A cables.

If you don't know what VRMS means, you have no business fooling with this stuff.
zydicious4 years ago
Wonderful instructable to inform the masses of this. First, this is indeed perfectly legal. When my ex-wife's business moved to newly built premises the jacks were actually set-up for this with only the actual wiring left to do when I set up all of their office equipment.
roadie.web4 years ago
Is there a length limit to this setup? I wanted to hook up my PS3 in my basement to a switch in the upper floor. This means it passes thru 2 floors (Basement - Main floor -Upper floor).

The Cat5 cable I'm planning on using is also carrying DSL signal. However, I'm just going to stream movies to the PS3, that means, when I'm downstairs watching movies, I won't be surfing the net.

I'm not looking for gigabit speed, maybe just 50Mbps for the HD movies that I stream; does it look like it's going to work for me? Thanks.
T3Hprogrammer (author)  roadie.web4 years ago
The length limit for cat5e cable is 100 meters, assuming you preserve all twisting at the terminators (max. of 1/2" untwisted). I would guess that a noisy DSL signal running right next to it would do no worse than halve that figure, so you should be good.
msalinas-14 years ago
What kind of jack is on the Bottom? That looks like one of those Kwik Jacks. Is that right?

JettaKnight6 years ago
This will work in a pinch. However, the noise coupled from the POTS, will induce errors (i.e. slower bit rate) onto the ethernet. It's certainly a good instructable since it's valuable information as long as you mind the caveats. One thing that hasn't been mentioned - lightening. If lightening strikes the phone line or near the line coming into your house it will be coupled on the ethernet; possibly destroying your switches and computers. For my house, I ran separate lines for phone and data. Several locations use the same data cable for two ethernet connections. And the line coming into my house is fiber so I don't worry about lightening, unless it's really, really bright.
T3Hprogrammer (author)  JettaKnight6 years ago
This is a very good point-- at our old house, lightning struck our cable line as it entered the house. We have Fios now, but there is still some copper near the house.
GLASS can conduct a lightning strike too. I just finished a project replacing a fiber that was melted by near lightning strike. Not properly grounded it took out the entire run including both closets and all the gear in them. The GLASS acted as a conduit for the strike to follow. Also learned this in a Fiber termination class for FIOS.
rondos6 years ago
there's nothing illegal or dangerous here, in fact the phone company sends both your internet signal and the phone line over the same pair of wire. It's called multiplexing.
cowen rondos5 years ago
No one saying its illegal or dangerous.

What s said is that the concept is faulty for today's standards.

Yes it may work but not to the fullest extent of the specifications design capability.
darrylm cowen5 years ago
Look, Cowen is right on this.

Is it illegal, not really but you better check your local laws and regulations. Being in this field for many years I can tell you that times are changing and some states now require a license electrician to install any copper, period.

Is it dangerous, no.

And, yes it will work but keep in mind that it will not be IF your system fails, it will be WHEN your system fails, because it will fail.

A great practice is if you are going to pull 1 cable to a location, why not just pull 2? Even if it is your house and you will never ever plug something into it, things change and usually in a short period of time when you are dealing with technology.

You should not put your POTS and Ethernet over the same cable. You will eventually run into failure. Keeping the 2 separate will eradicate any future problems. Does this mean you cannot run your phone over an Ethernet cable? No. You can, just dont run it on any spare pairs along with your data. Effectively, you can home run all your cables to the same panel, punch them all down the same way, most of us use 568B wiring scheme. If you need a phone in a location, you cross connect to your phone panel, and you can actually use a standard RJ11 plug in a RJ45 jack. This will use the blue/blue white pair (first pair on the jack). If you are needing multi-lines, it works just the same. Cross connect your second pair to the orange/orange white pair on the panel and voila, you have 2 lines at your jack.

Now, quite honestly I see no reason at all for any of this. If you run a dedicated POTS to one single location and have a wireless phone system, you would not need to have a phone line in every location.

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