Hack your House: Run both ethernet and phone over existing Cat-5 cable

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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Step 1: Theory

Picture of Theory
This is made possible because of the wasteful (some may say "spare") wires in cat-5 cable.

Cat 5 cable and RJ-45 jacks have eight wires.
Ethernet uses two pairs (four wires), one for send and one for receive.
Telephones use two wires.

Therefore, you can run both ethernet and telephone over the same wire, and still have two wires left over.

In fact, you could run two Ethernet jacks from a single cat-5 cable, or four telephone lines (though I don't know why you would run multiple phone lines.)

This Instructable will focus on changing wall plates from one RJ-45 (Ethernet) jack into one RJ-45 and one RJ-11 (phone) jack.

Note that I have not done extensive testing with cross-talk between phone and ethernet, though I have seen no degradation in the quality of either when both are in use.

Also note that this procedure will not work with PoE (Power over Ethernet) devices. Nothing bad will happen, it just won't transmit power. See step 13 for a possibly unsafe way to keep your PoE and add phone service. Also, it will not work with gigabit ethernet-- gigabit ethernet uses all four pairs. It will work fine at 10/100 Mbps which is sufficient for most people.

Step 2: Parts

1. A house wired with Cat 5 cable and RJ-45 jacks
  • To see if you are eligible, see check the three things shown in the picture. Your system also needs to converge at a central box where you can place an Ethernet switch or router.

2. An existing modular jack system.
  • Our house used Leviton QuickPort plates and jacks from Home Depot. This is not strictly necessary, but if you don't you will have to spend extra money on more jacks. This Instructable will assume you are augmenting your existing modular jack system.

3. Wall plates with an additional hole, one for each plate to be replaced
  • In my house, one two-port plate could be reused, but a three-port plate and many more two-port plates had to be purchased.

4. RJ-11 jacks, one for each plate to be replaced
  • If your house did not have modular RJ-45 jacks you will need to purchase those too.

5. Half of a 6-ft or longer phone cord, one cord per two jacks.

5. Either a multitool, or a screwdriver, pliers, wire cutters, wire strippers, and knife (razor helps.)

6. Soldering iron and decent soldering skills. "Helping hands" suggested.

In total, to rewire five jacks, I spent about $28. This cost does not go up linearly, as you can purchase items in bulk.

Step 3: Disassemble existing plate

Picture of Disassemble existing plate
Unscrew your plate from the wall. Pop out the RJ-45 port, and pull the wire out from the wall as far as you can.

Step 4: Remove a pair

Ethernet does not use the brown or blue pair in Cat-5. I chose to use the brown pair. You may use either.
  • Be warned that if you use the blue pair, your RJ-45 jack will no longer be able to carry phone service. However, you will hopefully have a separate phone jack soon, so this will not be a problem in the long run.

Using a knife or small screwdriver, break both of the brown wires as close to the jack as possible. Avoid all the other wires. If you break any of the other wires, you may have to redo the entire jack.

Using a knife, cut out a small section of the cable jacket about three inches from the jack.

Using a knife, screwdriver, or pliers, lift up the brown twisted pair and remove them so they stick out this hole.
  • I do not recommend using a knife to do this, as you may damage other wires.

Step 5: Crimp phone jack and reassemble

Picture of Crimp phone jack and reassemble
At this point, you need to establish a standard way of wiring the phone jack. It is a completely arbitrary choice.

Here is how I did it:
Brown Striped Cat 5 -> Red Telephone
Brown Solid Cat 5 -> Green Telephone

Follow the instructions on your phone jack to crimp the brown pair into the red and green wire slots on the jack. This must be done in the same order on every connection (see above.) Use a knife to trim the extra.

Once this is done, reassemble the jacks using a faceplate with one additional hole.

This end of the connection is now done.

Step 6: Locate head-end of cable

Picture of Locate head-end of cable
You will need to find the origin of the chosen cable. Mine were conveniently labeled and came with a paper showing where each one goes. If this is not the case for you, you may have to trace them using a cable tracer. You can borrow this from your local networking guru.

My cables were terminated with RJ-45 plugs. If you have jacks or loose wires, your job is easier.

Once you have located the other end of your cable, remove it from the panel. If possible, bring it to a flat surface you can work on.

Step 7: Remove a pair again

Picture of Remove a pair again
Using a knife, remove a small section of cable jacket as close to the RJ-45 plug as possible.
  • Now is not the time to damage wires-- if you do, you will have to crimp on a new RJ-45 plug, which means more money for parts and a second trip to your local networking guru for a crimper. However, if this happens, you can simply not crimp in the brown pair and not have to remove it afterwards. It's still not worth it to re-crimp the ends.

Using side cutters, clip the brown pair close to the plug.

Remove a small section of cable jacket a few inches from the RJ-45 plug, as you did in step 4.

Again, using a small screwdriver, pliers, or a knife if necessary, extract the brown pair so it sticks out from the cable two or three inches from the plug.

Step 8: Mutilate phone cable

Picture of Mutilate phone cable
Take a phone cable and cut it in half. You only need half of a cable per jack.

Inside you should find two wires surrounded by a jacket, similar to Cat 5 cable. Carefully cut and peel back the jacket, leaving an inch or two of wire sticking out. Trim the excess jacket.

Step 9: Select proper wires

Picture of Select proper wires
You need to figure out which wire in the phone cable is red and which is green. Mine were both physically colored black. To figure this out, you can find a phone cable that does have colored wires and use it for reference (you can see the colors sticking into the clear jacks.) You can also search online or use the picture provided here.

Step 10: Solder phone and Cat 5 together

Picture of Solder phone and Cat 5 together
Strip and solder the red phone wire to the striped brown Cat 5 wire, and the green phone wire to the sold brown Cat 5 wire.
  • I found it helpful to only strip the two wires I was going to solder together, to avoid mix-ups.

Tape the two wires separately to avoid shorting them together. Neither you nor the phone company would appreciate this. Tape the entire custom connection to the Cat 5 cable so that it appears nice and neat.

Step 11: Test

Picture of Test
Plug the RJ-45 plug into a router or switch, and your computer into the RJ-45 jack. Test this connection.

Plug the RJ-11 plug (the one on ex-telephone cord) into the phone junction panel.

Plug a phone into the RJ-11 jack. Listen for a dial tone.

Step 12: Troubleshooting

If both connections work, congratulations! You can get pretty fast at the process and do each jack in half an hour or less.

If the ethernet connection does not work, you need to find the problem in the wires. You may have accidentally cut an important wire trying to remove the brown pair from the jack. You may have also done this where you tried to remove the cable jacket.

In most cases, the only good way to fix this is to re-crimp the terminator onto the cable. Other fixes such as soldering will greatly degrade the quality of your connection. Remember that twisted-pairs in an ethernet cable can only be untwisted for half an inch on each end of the cable, or else crosstalk will occur.

If the phone connection has problems, first examine the physical wires. Most likely the bending or cutting of these wires has caused a break in them. If you find a break, it is acceptable to solder it to fix it-- phone is not as high-quality as ethernet. A multimeter may be helpful here.

Afterwards, check that your wires are attached to the proper place on the jack. One wire should go to the red terminal, and one to the green terminal. Do not confuse the green terminal with the solid green Cat 5 wire.

Finally, check that your wires are the same on both ends-- that is, brown striped to red, solid to green. Most likely it is a different problem, as long as you were diligent enough to double-check all the orientations.

Step 13: A few words on PoE

Picture of A few words on PoE
Power over Ethernet is a technology that allows ethernet devices such as access points to operate without the need for wall power. It is not used widely except in businesses.

It sends power by placing a potential between both brown wires (-) and both blue wires (+). Since you disconnect one of these pairs using this method, PoE will simply stop working (it is not dangerous to use PoE devices, the wires are simply disconnected.)

If you desperately need to use a low-power PoE device, you may get around this by only using one wire from each pair for phone. One example of this would be the striped brown wire and the striped blue wire. Then, the solid brown wire and solid blue wire would continue to work for PoE. However, this halves the maximum current that the cable can handle and may present a fire hazard when using large power-hungry devices. I do not recommend this, but it is a possibility.
mickeyaaaa29 days 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....

KenM46 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!!

Octataral8 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 ;)
MarcoManG611 months 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 Stonie2 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 cowen3 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 cowen3 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.

I think the point is to re-purpose existing wiring for ethernet without loosing your phone line. No need to pull any cable.
cowen dylanwinn5 years ago
The point is I make alot of money fixing this exact situation in homes and businesses that try it and then update later or re own the home and did not know that the EIA/TIA standards were not followed.
cowen darrylm5 years ago
Actually you are almost right. 568B is Orange on pins 1,2 Green on 3 and 6 Blue on 4,5 and Brown on 7,8 so for a pots line you would put line one of blue and line 2 on green not orange. A 3 line cable would use 2 and 7, 3 and 6, 4 and 5. 568A would be better used on the field end since blue and orange would be in the center of the RJ45 jack and then green and brown would be on the outside pairs. 1 2 3 4 5 6 7 8 RJ45 1 2 3 4 RJ 11 1 2 3 4 5 6 RJ12 RJ45 Data RJ11 Normal 2 line phone RJ12 3 line phone gold pins facing you. I had to make a fully custom cable using RJ45 jacks and RJ12 patch cords.
They may send it over the same line, but really by mixing your Phone and Ethernet in your house you are asking for trouble. Cross talk is going to kill your network speeds if you have any great lengths of cable. Cross talk is where 2 conductors are placed side by side and a voltage is run over one which induces a current in the other. Basically when you are on the phone you are going to be inducing a current in the data side of your network and that will lead to dropped packets and overall slow down. In the same way if you are doing anything that is network intensive and you are on the phone it is likely that you will hear static. When the phone company sends the signal over the same wire they send it on 2 different levels, thus why you get a phone filter to filter out the higher level noise that is data, but part of the internet modem that they give you converts it down into the same range as telephone. Basically what I am saying is yes, this is not terrible dangerous or illegal, but it really is not a great idea to wire your whole house this way due to the problems that can occur.
That's what the twisting is for. ;-) it minimized crosstalk.
That is the reason for the twisting, but it will not eliminate all cross talk. When your phone rings it sends 50v down the line which is just a huge cross talk creator. (and it hurt really bad if you are touching the wires at the time :] )
cowen Daleeburg5 years ago
Cheap legal way to get a BUZZ... Also you are the first to know that there is a call inbound. Safe way to teach you to respect electricity. It hurts like h%%%
rdn2 rondos5 years ago
Great discussion:
1) I do not know if this is an issue or not for building codes. Not saying it is or not, I just dont know, and the building inspector would have the jurisdiction for wiring inside your house, not the phoen company. 

2) For the discussion on DSL sharing the same line and the DSL splitter: DSL service can be over the same line as the telephone service, or on a seperate line. Some service provisers only provided it over a second line for regluatory and tarrif reasons. If on a seperate service, then there is little or no crosstalk between the services. 

When sharing the same line, DSL is on higher frequencies than you can hear, so in many cases, everythign will be fine if the DSL modem is connected to the phone jack without installing splitters (which are filters) in front of the voice lines. However, depending on your particular phone, the higher frequencies of the DSL can cause intermodulation and create noise on the voice line. The filters are designed to take care of that noise. Most phone companies tell you to put the splitter there because it is easier and cheaper to put it there for everyone, than have a service or customer service call for the phone devices that pick up noise from the DSL line.  

I disagree, I have verizon for phone, and mediacom for internet and television. I have dealt with wiring in my basement, and I have all seperate lines. Quite possibly, though, the coax is just split into two somewhere underground. It depends on when your house was built, when the lines were buried, and when you signed up. I think what you are referring to is dial up, it is simply the computer using the phone to connect to another modem. To send and receive data, it makes beeps and loud screaming noises that make my ears bleed.
If you have Verizon for phone and cable for Internet then obviously you have all separate lines. If you have DSL Internet it would come in on the same pair of copper wires as your telephone.
jongscx5 years ago
In regards to the POE setup, it would be better to use one pair (brown) for power and the other for voice (blue). It doesn't matter really which, but if you do it as you'd suggested, you would be running a power line next to a signal line, and twisting them together in fact. The twisting is what (to put it simply) prevents this type of interference.
cowen jongscx5 years ago
Some configurations of equipment use the blue and brown to provide the POE over the cable and thus splitting the cable can FRY your phones.
T3Hprogrammer (author)  cowen5 years ago
This is what I thought at first. But, by splicing in the telephone cable, you disconnect the blue or brown pair from the ethernet connectors at either end. So, connecting a POE device will not harm the telephone board, since the power wouldn't get past the jack (the transmitting pairs have been snipped). Likewise, a POE source, like a switch, would not harm telephones, because the necessary pairs have been cut on that end too. An easy way to think about this is that you're carrying two things in one cable jacket. You could remove the jacket and split apart the telephone pair and the ethernet pairs along the entire cable run, effectively making two cables. They are completely isolated. Two pins on each of the ethernet connectors will be disconnected. I don't recommend doing this, it's just a mental picture to demonstrate how the phone and ethernet will never interfere with each other, except potentially through induced EMF (no pun intended). However, this effect is negligible, especially in the telephone wires. I believe it is negligible in the ethernet wires too, but there is some disagreement to that regard.
EIA/TIA standards and the way some manufactures make their POE equipment will use the BROWN and BLUE pairs in a cable for the POE. So the PAIRS for the Blue would be one side of the power and the Brown would be the other side of the power. Example: DC is not very effective and can require Positive and Negative to run across the blue paired and brown paired cables for efficiency of the POE requirements of the device. This is to get a better conductive path along the cable and prevent over loading conditions. The same can be for the AC versions of the POE devices. it is just not a good idea to split any data cables and to follow established practices and standards of EIA/TIA and the NEC when if come to Power. I have been doing this for 13 years and the failures that come with this are more then the success rates. But I love to diagnose these makes the rent payments every month.
xsk8er90005 years ago
 This is actually how alot of telco companies do it. They do it to save money. In my eyes this is not a good idea. It limits you to using 10/100mbps which if thats all you need, cool.. But gigabit uses all 8 channels if I remember correctly and also the two signals would give interference two each other so when both the phone and that network connection were active you would get some interference. Obviously there are a lot of variables to this.

Many that do this are splitting a cable that is a Voice cable not a Data cable.

Professionals with integrity would not conceive of this as a permanent design.
hintss cowen5 years ago
actually, it was a data cable designed so it could be voice or data, and he made it both
cowen hintss5 years ago
This configuration would work for 10 meg and inconsistent 100meg The ENTIRE purpose of the 4 pairs is to provide shielding of the cable unto itself. If you run screened twisted pair (STP) as long as the entire run gets grounded the twisted pairs are not so much shielding as the screening is the shield. The WHOLE purpose of the DESIGN behind CAT5, 5Ehanced, CAT6, and DRAFT CAT7 is to provide noise reduction on the cable and balance itself from alien cross talk of nearby cables, motors, ballasts and other noise creating electrical devices. The EIA/TIA standards as well as BICSI are setup that a DATA cable be completely terminated to one jack so that ANY device my use the cable with out regard if it is a House phone, Ethernet signal, Token Ring, or other, Data speeds from 1 meg to 1000 meg are able to transverse a PROPERLY configured EIA/TIA terminated cable.. Standards are introduced in the industry for a reason. We follow these rules so that future expansion is possible when the original home owner dies or moves and the home is turned over to someone else.
Dr Qui5 years ago
In my network technician days I would often use this trick to split a cat 5 cable to network 2 PC's on 1 cable.

It was a simple way of avoiding the disruption of running long cables through busy offices.

Keep up the good work.

apr16945 years ago
same for CAT6 cable?
T3Hprogrammer (author)  apr16945 years ago
Cat6, for the purposes of this instructable, is identical to Cat5(e). A few of the cable runs in my house (newer self-installed ones) were Cat6.
ScubaSteve6 years ago
So, Theoretically, you could be able to make a LAN network wusing the existing 4-conductor telephone wire in your house? (I believe its CAT3) I know you can rout it through wires with only 4 conductors, becasuse the Ethernet cable my ISP gave me with my modem only has 4 conductors in it, but has an RJ-45 jack on the end.
yes... theoretically. but only for very short runs, as it doesn't have the twisting that cat5(e) has. this allows for longer wire runs by shielding the wire... with itself.
T3Hprogrammer (author)  ScubaSteve6 years ago
Like corencano pointed out, you can, if the wires are in twisted in two pairs. However, unless you have 6 or more wires, you can only run phone or ethernet, not both.
Slightly correct. The wires have to be twisted - If they aren't, they will interfere with each other (This is true for most distances over six feet). The router sends two, identical waves, one positive, over negative over the twisted pair. The resulting interference is canceled out, as a result of the negative-positive averaging the other out.
Yes, the negative and positive are required to eliminate crosstalk. I wanted to point out how they cancel each other out. Any current through a conductor also generates a magnetic field around the conductor. (If you hold your hand as a fist and stick your thumb up, your thumb represents the current through the wire, and the fingers represent the direction of the magnetic field.) By sending the exact opposite current down an adjacent wire (e.g. in a twisted pair), the two magnetic fields are cancelled out and the crosstalk is eliminated.
T3Hprogrammer (author)  bradhouser5 years ago
Good explanation. Your explanation helps explain how the wires don't generate any interference. Additionally, the pairing of the wires makes it hard for the pair to pick up interference, too. On the cable, the receiving end looks for a potential difference between the two wires in a pair. By twisting the wires and putting them so close to each other, any induced voltage will probably be induced into both wires. Therefore, the induced voltage doesn't change the potential difference between the wires, so the data should still transmit clearly.
Oh you mean ATT cable...

Red Green Black Yellow (White Blue)
Normal 4 conductor cable is not cat3 Cat3 is an 8 conductor cable. Cat3 cable would only be good for either short runs of 100TX ethernet or 10TX also this won't work if you want to use Gigabit Ethernet. (1000TX) GigE uses all 8 wires for networking. in such a case, this setup would FRY something
You can run ethernet over cat3, but no guarantees about signal quality - short short runs of 100M or longer runs of 10 meg are possible but again less stable.
SinAmos5 years ago
AF-Geek6 years ago
Isn't this what Cat5 was created for? I understood that the whole Idea was to run data and voice over the same line, thus the four pairs: 2 for data, and two for voice (standard used to be to wire an RJ-11 for two lines). Another caveat to this idea: You must have a "home-run" type system; i.e.: all cables must run from jack to central distribution box without breaks or splices. BTW: I did this when I discovered my new house was wired with Cat5 (did my neighbor's, too!). Mine was easier because it had terminal blocks.
cowen AF-Geek5 years ago
USOC has either 2 4 or 6 pins in a RJ11 type jack VOICE

Pins as you look at them are for a 6 position jack
6,1 line three green
5,2 for line two Orange
4,3 for line one Blue (these are the center pins)
Brown spare

Pins as you look at them are for a 4 position jack
1,4 for line two Orange
2,3 for line one Blue (these are the center pins)
Green spare
Brown spare

Pins as you look at them are for a RARE 2 position jack
1,2 for line one Blue (these are the center pins)
Orange spare
Green spare
Brown spare

568B has 8 and 568A does as well the only difference between these are the green and orange pairs are flipped. 10/100 non duplex uses 2 pair, duplex mode depends on the wasted spares for ground.  1000M uses all 4 pairs.  That being said your switch and network cards must all support 1000M in order to run that speed just because you have the best cable does not mandate that you can run the speed everything must have the highest capability.

B Term
1,2 are orange
3,6 are green
4,5 are blue
7,8 are brown

A Term is closer to the USOC standard, 568A and B are used together for a cross over cable.  There used to be a Government mandate that all Government connections were A, that has been retired and is now on demand use only.

1,2 is Green
3,6 is Orange,
4,5 is Blue
7,8 is Brown

Usually if a cable is run we will split blue and orange out on to a jack and green and brown onto another.  This way 2 line phones can be used on both jacks and in the back we cross connect the incoming line to that pair for that station cable.

From this snippet you can see there is a purpose to the extra wasteful cables.

Now just because you have 1Gig bit (1000Meg) in the network if your DSL is a whopping 748K/360K you have only managed to spend a lot of time on making your in house wiring the best of the entire network.

This will help in the case of older homes with old cable or offices that have lacking cable infrastructures.
cowen AF-Geek5 years ago
Yes it is but not to as you split the cable.

The blue pair is line one of a phone 4,5
the next pairs out are line two 3,6
the next ones out are line three 2,7

and if you have someone make you a specialty cable the last ones would be 1,8.

Now that would be a hack.

If you follow spec then we need to know what you are doing 568a or B

Depending on what you are plugging in is what pairs are used.  Most often it is B so that is what we would follow here. For a Voice line Blue is line one.  Orange and Green are Ethernet data lines Brown is extra.

Oh you say thats what this is about.  NO depending on what you are hooking up the Brown and Blue is ground for Data or POE for devices that need to be powered such as IP phones.

Depending on what you are hooking up is what each pair is used for.  Somethings are more forgiving then others.
matbh AF-Geek6 years ago
thats right! this is not a hack! the brown pair can be used for video too. u can find this standards in the furukawa documentation...
ReCreate6 years ago
Wow, Genius, Do you think its safe to run 40+ Volts through those Cat5 cables so close to all the others? Won't it cause any interference of some kind?
Yes it is safe, most commercial POE solutions run 48 volts AC over the unused pairs. The voltage is high so the current is low.
OK. I see your point.

First, the insulation in those CAT5 is quite good, I'd say at least 100V. But I can see your point. But if you are worried about current near the data wires, then I'l explain.

My router uses 9V at 1A. Ohm's law states that
Where P is power in watts, V is voltage, and I is current.

So, my router uses 9 watts.

If you sent 48v over a cable, lets say 50v when it is rectified,

if we reverse ohms law, we see that

I = P/V

so 9W divided by 48V equals ~0.19A. That's only 190mA. No risk at all of interference. Hope that answers your question.
cowen Da_Fudge5 years ago
Is that DC filtered or unfiltered?

Have you ever heard the wine from the alternator over your radio in your car?

DC needs to be heavily filtered to be clean.  Any time you have DC with a frequency more then 0 (zero) there is noise being produced DC or AC.

Splitting a Data cable with anything else is just bad design.

That is why companies install 2 cables or more and dedicate one as Voice and one as Data.
Ohms law V=I*R
There are many different 'forms' of the law, each for finding out diffent things, example, if you had current and resistance and wanted to know the voltage, you would use the formula you just showed,


And if you had Voltage and current, use my first formula,


And finally, if you know the power and the voltage, but want to know the current, use


A wheel with all the formula's and there derivatives can be seen here.
Ohhhh i seee sorry my brain is being slow, its just changing the equation because power is a function of I and V. God i feel stupid now, and im learning this at college :|
T3Hprogrammer (author)  Da_Fudge6 years ago
It's not the current that causes interference, it is the changes in current. These changes can create a changing magnetic field, which will induce a current in the data wires and disrupt the signal. This is why it is not recommended to run Cat-5 parallel to power lines, since the current changes direction 60 times per second. DC is not an issue. In fact, there is an alternate PoE concept which runs the power over the data wires.
but luckily someone, back in the Edison days, invented twisted pairs. where each color is twisted to it's solid or striped friend :) since the wires are twisted each wire's magnetic field is canceled out by its partner's field. virtually no crosstalk between the channels (colors). however, 4-wire phone cable is flat and unsuitable for high-speed data or audio transmission
O_o Ok i get it know...
and the phone 'ring' is anywhere around 70 volts AC depending on your location. It uses the same gauge wire as standard phone cable cat3 - the wire can handle it - but the noise is literally huge compared to what the ethernet standard is designed to handle.
In the US, the ring voltage is around 90VDC, not AC. Getting zapped by ring voltage hurts a lot worse than sticking your finger in a wall socket.
No. Get your facts right. The ring signal is 48 to 100 volts AC. (this varies depending on your telephone company)

Your wall socket will hurt a lot more than a ring signal. In fact, your wall socket will kill you.

The ring signal is safe because the current is limited and because it is 20-30 Hz, which is less painful.
"The telephone company sends a ringing signal which is an AC waveform. Although the common frequency used in the United States is 20 HZ and in Europe is typically 25 Hz, it can be any frequency between 15 and 68 Hz. Most of the world uses frequencies between 20 and 40 Hz. The voltage at the subscribers end depends upon loop length and number of ringers attached to the line; it could be between 40 and 150 Volts. The ringing cadence - the timing of ringing to pause - varies from telephone company to company. "

T3Hprogrammer (author)  frollard6 years ago
My physics are not great, but I believe that this frequency is low enough to not resonate with the ethernet transformers, though I am not certain. It is also low-current. I would be more worried if it was in the kilohertz or megahertz, perhaps a DSL signal.
Hmmm, I could have sworn at one time they were using DC for the ring signal in the US but it would appear that that was never the case or changed at some point. Either way it still hurts like the devil when you're touching those wires at the wrong time.
Sagewah oritpro6 years ago
True. I can say from bitter experience that IT DOESN'T BLOODY TICKLE! I figured the tingling up my arm when I was tinning the end of a cable was poor earthing on my iron. I only learned it wasn't when I went to strip a little more of the shielding a bit later - with my teeth... Disclaimer: was a looong time ago, learned lots since then.
srilyk Sagewah6 years ago
Reminds me of the moment in time my dad and I were running more phone lines throughout the house. In Arkansas in the summer evening it was still 80+ degrees so I was sweating quite well. The wire connected to the phone company decided it would touch my nice and sweaty upper lip. THAT was a night to remember!
Its actually more close to 100V...
Its DC power for POE. 48v and max 350ma.
gavins5 years ago
Let me start by saying I work for "The Phone Company" I have been a repairman on the phone side and now I currently work in the new IPTV side doing installs and repair. What you do with the wiring after any companys box at your power meter is usually of no concern to us. If you decide to run Ethernet and telephone over the same cable you will introduce noice and crosstalk. Which we can then bill you for to repair, by running a stand alone line for your telephone. On occasion we run our IPTV signals or our VDSL signal over the same line as your telephone but our equipment is designed to filter out the "noise" that is incurred by such wiring. I would reccommend dropping stand alone cabling for all internal ethernet wiring. This gives you a broader range of flexibility and believe it or not those "pairs in your inside wiring do tend to go bad especially when they meet at an external point on your home. It only takes about 30 mins to drop a wall with brand new cable and you can put a junction in the attic where you can access at any time and rewire as you see fit and not worry about The big bad phone or cable company caring. And on a side note your telephone line if you have one is 52 volts DC provided by 48 volt batteries. And the ring voltage is around 100 volts AC. of course this will vary with distance and resistance and all the other good stuff that works its magic on circuits.
cowen gavins5 years ago

In a pinch you can split but for normal operations install as many cables as you need to get it done.

Networks only need 2 pair but the other 2 pair are there to help cancel out the Noise that is caused in environments.  POE uses brown or brown and blue depending on equipment.  Under normal citations these pairs are grounded by the equipment.

10/100 meg or in a pinch 1000 meg

Duplex mode.

The list goes on and on.  In a house all most want are a connection and do not care that splitting cables actual hurts the networks capability.

But I like customers like this that mess around and then need it fixed.
rondos6 years ago
The phone company sends an analog phone signal and a digital data signal to your house over one pair of wire, over a distance of several miles from their central office. When the wire enters your building, the two signals are split off onto separate pairs of wire, one pair of which are for your phone. The other pair goes to your DSL modem. This instructable shows how to run both over an existing Cat-5 cable. Key word here is "existing". This is very doable but is not good design practice. When you examine a section of Cat-5 cable you'll notice that the four twisted pairs of wire have different twist rates. The purpose is to eliminate (reduce to the point of irrelevance, actually), crosstalk between the various pairs. But this is a hack for existing cable. If you are cabling a building during a remodel, this is not good practice because if/when you want to expand your network to gighertz speeds, you will need all eight wires for your ethernet network. If you have phone service from the phone company and internet connection from your cable company, this hack does not apply to you in any case.
T3Hprogrammer (author)  rondos6 years ago
I do not have DSL, I have FIOS, which is sent over coax cable. The cable goes to my cable modem. I made this connection at the point where whatever comes into the house has been split (demultiplexed?) into phone and ethernet, i.e. after all of their hardware and my modem. It can be done on any system that uses standard analog telephone service and any form of ethernet (including DSL, cable, or even dial-up if you have a central hub/swich/router (unlikely)) I completely agree that this is not good practice, and was only to avoid pulling new wire.
I thought FIOS was sent to your house over fiber (FIOS)?
FIOS is sent from Verizon stations to a routing box in your house by fiber optic cabling, but after that it's standard coax and Ethernet lines to end usage.
 That was kinda what I said...Sent to your house over Fiber...
darthneo rondos5 years ago
I believe you are wrong, on my DSL filter there is only 1 pair of wires that go into it (2 wires total), and it splits it to my DSL and Phone (1 pair each) there's no way you can take 1 pair and make it into 2 completely separate pairs.... from what i remember being told, your voice uses a certain frequency, so the phone company uses the unused frequencies above that to send analog data communication... hence DSL MODEM -> MOdulation/DEModulation, which deals with analog.. (filters are used to keep those upper frequencies from interfearing with your phone call and vise-versa) And just if you or anyone else is wondering, the frequencies above voice frequencies are split in 'blocks' and each block is used for analog data transmission, and the more blocks used by the modem the faster the connection... i think each block can run at aprx 54Kbps, i think the theoretical max speed is 64Kbps each, hence why dial-up runs at aprx 54Kbps its using 1 channel (the voice channel)
whiteboy65 years ago
they ran ares like that when they installed i hace dsl and did away with filters and just did the same exact thing u did, GOOD THINKING THOUGH
Goodhart6 years ago
In your Disclaimer portion, you wrote: However, if you do everything right, they won't care.

This is true up to a point. If you have phone line issues in the future, and they have to work on your lines in the house, there may be a bit of disgruntlement expressed over the set up :-)
sturific6 years ago
I don't understand why you didn't just break into the cat 5 you where using as a phone line and run the other phone lines all on it.
T3Hprogrammer (author)  sturific6 years ago
We only have one phone line, with many cables going from a central breakout panel to each room of the house. Since I also wanted an ethernet connection at each room of the house, I had to run the ethernet and telephone over the same cable. The issue here is where the wires go.
desidude526 years ago
Not the best idea. I've done this actually and it does really kill the network speeds. Along with that I get disconnected from my messengers every time the phone rings. But anyways this was a good idea maybe a year ago, but now wireless is dirt cheap now. I've got all my computers wireless now, makes it easier when your moving around too.
T3Hprogrammer (author)  desidude526 years ago
I have not had any problems with disconnections, and have tested latency and lost "pings" when the phone is ringing and in use. As always, your mileage may vary, and is highly dependent on the length of the cable runs and the quality of the splicing. Our whole house is also wireless, but, ironically, it suffered interference from our 2.4 GHz wireless phones. Switching to wired gave a huge boost in reliability for about the price of replacing one wireless phone.
rondos6 years ago
this was an instructable about phone lines and data lines over telco service, not cable. The phone company sends DSL and phone service to your house over one (1) pair of wire, meaning both signals are travelling on the one pair of wire simultaneously. At the demark point the signals are routed onto separate sets of wire, one pair to your computer, another to your phones. In new houses or for tech savvy occupants, Cat-5 cable is the cable of choice, and maybe your personal preference is to run a separate cable to each access point even. But it's not necessary, since you probably should be using a switch in your computer network, not a hub. Now if you're taking your phone and network off your cable line, maybe you have a point, but I don't think so. In the case of cable service, the phone, your network and the TV signals are all being run over one cable connection, simultaneously. This concept has nothing to do with dial-up. How do I know this? Well I'm a cable technician.
kiwisaft6 years ago
i made something like thad when wiring my house, but i just jused network jacks where you can wire the backside freely. this is more confortable than crimping and soldering cables.
pepijn_6 years ago
I layed the cables a month ago :( By the way, why do you use CAT5 instead of CAT5e ?
T3Hprogrammer (author)  pepijn_6 years ago
I used whatever was in my house from when it was built, which I think is CAT5e.
ARJOON6 years ago
it works a bit just like usb cable. 1.Data+ 2.Data- 3.Volt+ 4.Volt- if the data cables are used interference is caused as there are 2 types of frequencies. 2 refresh rate per milicentieme(zeroes and ones)
ARJOON ARJOON6 years ago
more details (o,1) are the current beats
The way you handle that knife is an accident waiting to happen :P. Haven't you ever heard of the saying "Cut your chum, not your thumb"?
frollard6 years ago
I did this with my home network when the condo contractor took my instruction of 'I want ethernet to all the phone locations' as "I want ONLY ethernet to the phone locations". It worked, but very poorly at 100mbit. Network was excellent, phone was excellent, but the line noise during a phone ring destroyed the connection and required the router to reboot before it would function again...every time the phone rang. I ended up nixing the phone.
reply to self - addendum - I also had the adsl running on the same phone line - but not on the 'hybrid' line - adsl was in the wire room next to the panel - but the noise from all the doubled lines in the house caused enough interference needing me to reboot both the modem and the router.
BlueFusion6 years ago
As noted, it won't work with GbE (Gigabit), or (i wish) 10Gbase-Tx (10Gbit ethernet standard, requires cat6a or cat7 cabling, usually restricted to high end stuff like datacentres). However worth noting is that merely using cat5e or cat6 cabling even on 100mbit standard fast ethernet can result in a decrease in latency (lag) and on longer runs, fewer dropped packets, both of which are good for gaming and general network performance. Also having recently (yesterday) run yet another ethernet cable through the roof to my bedroom, it's often not as much of a drama as it may seem to install new cabling. I'd say it's worthwhile for the performance benefit, and less hassle. Plus, cabling isn't all that expensive. Cat6 cable is usually only about 30-50 US cents per foot (if my maths serves me right; converting from Australian dollars and from metric). All up though nice job :) very neat hack.
Padlock6 years ago
This is standard practice for most larger business. For example, the entire University of Notre Dame dorms and classrooms are wired this way.
corencano6 years ago
Oh and you can use CAT3 wire also, as long as its twisted. If the wires aren't twisted inside the shield you will get crosstalk on run over 20ft or so and connection wont work
corencano6 years ago
This works only sometimes. You absolutely must use a 10/100 switch or router only. When using a couple different consumer grade 10/100/1000 switches or routers they have trouble auto negotiating the 100 mbs connection. Since you are only using 2 pairs or 4 wires you wont get a gigabit connection anyways but like I said low end equipment has trouble negotiating I am a home automation specialist and we do this whenever we run into a pinch. We don't make this regular practices
luvit6 years ago
are you saying that i could've had wired internet instead of wireless? so cool !
Cat 5 is now used for most if not all telephone installation use 2 pair Cat 5 also by doing this you limit your self to 100Mb due to 1000Mb requires the use of all 4 pairs of wires even though the the cable is not cat5e it still may support the 1000Mb speeds, so it really just depends on your needs as to what you do
wcbzero6 years ago
Do know that if you ever want to use this cable a achieve gigabit speeds, this will not work. Gigabit requires the use of all 4 pairs (all 8 wires).
T3Hprogrammer (author)  wcbzero6 years ago
I added a note on the theory page noting that it will not work with gigabit.
bware6 years ago
Logged in to point out the issue with Gigabit (and beyond). However can confirm that this works find in practice.