Cat5 Data Cabling Phone Works Data Doesn't

Question

I am working in a customers home and they have a home full of cat5 cabling. I have put a router in the main network hub where all the cables from the house come in. I have used a phone to identify a cable and I plugged one end into the router and at the wall plate I plugged in an access point.

My problem is, the line works perfectly fine, clear audio for a telephone. But with data there is no response, no blinking lights, its just like the device isn't connected (but it is).

I thought to myself maybe the person who installed the cabling only connected the required pairs for telecom but not for data. So I took the wall plate off the wall and sure enough only the blue pair was connected. I used a 110 punchdown tool to punchdown the cable to match the standard found at the main hub. T568-A. But the data still doesn't work on any of the ports apart from 1.

So far I have tried using every other wall plate in the home. The only one that worked was one in the study (after me having to punchdown the data pairs).

Interestingly enough, after talking to the home owner, he studied electrical engineering. He also has no idea why phone works and data doesn't.

We thought their could be such thing as a telephone only jack. So that even when you punched down data is still wasn't electrically connected.

Extra notes.

• ALL the ports in the house on the walls and in the main hub are all RJ-45 Cat5 (we think). Their is no RJ12/RJ11 plugs in the home.
• The study port only worked after I terminated the data pins.
• We have tried almost every cable in the home.
• PoE support is required on the line once up

Any help is greatly appreciated, thanks in advance.

Answer 1

After all this. I have solved the problem. In the house their was two cables that went to each room. let's say each room had cable a and cable b. At the hub end a was terminated and b was just hanging at the back. In the rooms a and b was terminated on top of each other but only the phone pairs. When we used the other wires in the hub everything worked fine. The cable testers showed that the telephone pairs were fine but the others weren't connected that's what hinted us to look for the other lot of cabling. It is all so confusing and too hard to explain in words. Thank you everyone for your help!

EDIT: The cabling was Cat5. We found writing one the cables in the duct that carried cables through floors.

Answer 2

1. Make sure that it's punched down the same on both sides (choose A or B)
2. Make sure the cable is actually rated at Cat.5

Why this will do voice lines: The two inner lines on 8P8C are arranged the same as on 4P4C connectors (You often call these RJ45 and RJ11 respectively). The outside pairs are then grouped. This meant that a business could upgrade the cable and still use analog phones up to two lines before converting over to digital.

My attempt at a view:

4P4C______________________________ 8P8C (see the little 4P4C inside the 8P8C)

2-1-1-2 (Data lines 1 and 2)______ 3-3-|2-1-1-2|-4-4 (Data lines 1-4)

Answer 3

The pairs in use for phone are 4-5 for line 1 and 3-6 for line 2. Each line only requires 2 wires.

For Ethernet 10 and 100 base, 1-2 and 3-6 must be connected as a minimum. Ethernet requires one pair for transmit, other for receive. For Gig base, must also have 4-5 and 7-8. May require better cable. POE also requires those to be connected as power is sent over them.

So if only the 4-5 pair is connected that's why the phone works, not Ethernet. Test your wiring - get a checker and plug one end into the wall jack, other on the other side of the cabling and it will see if all the pairs are connected correctly.

Answer 4

I suspect its depressingly common for electricians to claim they can wire up a house for data, and then do it wrong (its happened to me once, nearly multiple times, and the data wholesalers I use say its a common problem).

It sounds to me like the house has been wired incorrectly - most likely they have simply daisy-chained pair one between points, rather then running seperate cables back to a central point. If they have done this, you are SoL, and may want to look at an alternative solution (WIFI, PoE) to get round the problem - or maybe you can pull cables and rewire the house.

You should get yourself a cable tester. These are inexpensive devices (about US$10 - for the one I found on Amazon), and plug in each end of the cable to test you have continuity on all the pins, and that there are no crossed wires.

Answer 5

It is possible that pairs got miswired. As other answers have pointed out, ethernet uses the outside pairs for 10BaseT and 100BaseTX. The pairs will autonegotiate for TX/RX on most modern hardware, if an outer pair got swapped to an inner pair then the cabling is no good. The pairs use differential signalling so swapping - and + on a pair is no good as well. If you suspect only the inner pairs are connected and its Cat5 Cabling you could make try making a quick crossover cable to swap the inner and outer pairs and test if you can bring the data network up.

Otherwise no lights = no link, a link is a negotiated connection between PHY's on either side of the cable, meaning an sustained electrical connection is maintained between chips on either side. Keep in mind that if the link comes up in 10BaseT mode then the amber light will not light up on a typical network card.

It may still test good with a continuity meter, if the cabling is OK for continuity and the link isn't established this means that the cabling does not meet 802.3 Physical Layer spec. If it is Cat5 I would not expect any sustainable 1000TX link maybe 1000T for short runs but you should really use Cat5E. But I would expect reliable 10BasetT and 100BaseTX links.

If it is Cat3 cabling then 10BaseT will be the only possible link that could be brought up, and runs of 100M is the theoretical maximum but in reality likely much less. You can easily tell Cat3 from Cat5 because the shield is missing, if you don't see a little bit of foil in your junction box from the end of each cable or you can easily feel individual conductors through the cabling insulation then it is Cat3.