Sharing one Cat5/6 Cable for Internet/Phone

or

Wire phone and data on one cat5 cable?

10BASE-T and 100BASE-TX only require two pairs to operate, located on pins 1 plus 2 and pins 3 plus 6. Since 10BASE-T and 100BASE-TX need only two pairs and Category 5 cable has four pairs, it is possible, but not standards compliant, to run two network connections (or a network connection and two phone lines) over a Category 5 cable ..... switches and PCs internally hardwire pins 4–5 together and pins 7–8 together, thereby creating a short-circuit across each "unused" pair.

..... 1000BASE-T requires all four pairs to operate............ http://en.wikipedia.org/wiki/Ethernet_over_twisted_pair

The phone line only requires 1 pair, but ethernet usually requires 2 pair. So you can run both over the same cable, but the pairs would need to be split. [?? -FNC]

Standard 10meg and 100meg ethernet use the orange and green pair. So the blue and brown pair are available for phone lines. However, you would want two jacks in the wall plate one that has the orange and green pairs wired for internet in an RJ-45 jack and one with the blue and brown pairs on an RJ-11 Jack. On the other end, you would need to split the orange and green pairs from the blue and brown pairs as well. 

I wouldn't recommend this if you are running new wire, however it works fine if you can't run new wire. 

A major caveat... Gigabit Ethernet uses all four pairs so this won't work for gigE.

Also, when a phone rings, it sends a much higher voltage signal down the phone line to power the ringer. This can cause interference in the network lines since they are intertwined together in one wire.  Not only will the ring voltage cause interference, it can actually cause damage to the devices using the other pairs in the cable bundle for network connectivity. 

When I called the guy to rewire my house, he mentioned I could do data and phone over one CAT5e. I was happy to discover this as some of the rooms were not so important to have gigabit speed.

I have tested the lines where the cable is shared and I don't have any interference. I get constant throughput (pretty much full 100mbits/sec) while transferring files when the phone rings or when in use. No problems what so ever.

I think this is done in practice quite a bit. There is a lot of reference to this on the internet. 

Here is a quote someone from another forum:

"I have had to mix Ethernet and POTS phone lines on a single CAT5 cable many times. Never had any issues yet what so ever.
Just keep pairs separated for Data & Phone. I usually use the Green and Brown pairs for Data. Using 586B punch Green on Green and Brown on Orange.
Note this will only give you 100 Base TX, you cannot use POE (Power Over Ethernet) or 1000 Base T in this configuration.
Not ideal, however, many times this is better than wireless and saves time when there are not separate Voice & Data drops."

Ring voltage is 90VAC at 20hz. 
Talk battery on-hook is 48 volts.
Off hook (dial tone and voice) voltage is 5vdc. 
Positive side is green, ground side is red (opposite of what you would expect.) [Second guy: There is no positive....it's -48VDC WRT ground. Third guy: yea. We are talking voltage across the line pair, not earth. First guy: uhhh, yeah...one of those wires is grounded (earth)...the other is at a -ve potential relative to it (earth)....so, "we're" talking about the same thing.] 

New phones with piezo ringers and not actual bells do not induce major current spikes on the line during ring cycles and as such are generally OK in CAT5 cabling with the 2 ethernet pairs in use. 

Many homes are wired with what LOOKS like unjacketed CAT-5 but it is not. The unjacketed multi-pair cabling is called E-station. It is a CAT3 cable, not suitable for ethernet use. It was designed for multi line phone installs or, in some apartments, the pairs are split between adjacent apartments.

25 Aug 06 15:35

Reminds me way back when..we had splitters on both end to take advantage of all cables for both voice and data in one sheath. The data speeds at that time were slow (<mbps) so no problems. But today, the higher speed data mixed with the lower speed voice WILL cause bleeds, feeds and aliens.

5 Sep 06 18:23

I have actually done this recently in a new home that was pre-wired all CAT-5e. It works great. I have put a tester on the network and tested it and I get a full 100base-t. Pins 7 and 8 [The T568A 8 is brown and 7 is white/brown.] are used for Power in PoE applications. Separating them for voice, does not affect the network. As stated before, best practices says "NO", but it does work very well for a home network. I just punched down the first 3 pairs to a 568b block and the brown pair to another block. I really liked my results. I would do it again, if I had the same situation. If you have the choice of running 2 cables in a new buildout, absolutely run 2 cables.

johnQ February 5, 2010 at 07:42:13 Pacific "I know Cat5e cables only use four out of the eight wires in the cable. I wanted to know what wires are actually being used."

You're mistaken. The number of wires used depends on the bandwidth of the connection, not the type of cable. 10/100 use 4 wires (2 pair) and 1000 Mbps requires all 8 (4 pair). This is true for Cat5, 5e, 6, and 7.

I'm guessing you want to know which two pair 100 Mbps uses. A quick google search would have yielded your answer.

The answer is, 10/100 Mbps use 1, 2, 3 and 6. [For the preferred T568A (as opposed to T568B) 1 is white/green and 2 is green. 3 is white/orange and 6 is orange.]

Now that answer won't really be useful to you unless you know the A and B standards for cabling so this time, use google and go find that info.

So, In Unit 11E we are going to do the following with the single Cat5e number 1 run. (This run essentially terminates in Unit 11E's southwest corner, but is daisy-chained to two additional outlets along the south wall.)

Since both telephone and internet want to use Orange, this plan substitutes Brown ( not essential for internet) where telephone would normally use Orange. Thus wire colors are all 'normal' except for Orange telephone.

This approach above makes it a bit easier to get the internet right.

The approach below makes it a bit easier to get telephone line 2 right.

Since both telephone and internet want to use Orange, the plan below substitutes Brown ( not essential for internet) where internet would normally use Orange. Thus wire colors are all 'normal' except for Orange internet.

A system wired in either way should function identically! That is, Telephone lines 1 and 2 and 10 or 100 megabit (but not gigabit) ethernet should all be available -- in exactly the same way.