I have been planning to set up a wireless network in my room. But due to old cables installation. I couldn't do it. So I thought of an idea of combining two rj11 port into one rj45 port. Is it possible? If its yes, how would be the connection speed? I think the old cable installation most probably cat3. Thank you

  • You must make sure that the Category-3 telephone cable is not tapped anywhere along the path. It usually is. This will not work for network connections if it is. – Ron Maupin Aug 31 '16 at 13:57
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer. – Ron Maupin Aug 15 '17 at 1:42

As stated, you can actually run Ethernet over any two or four twisted pairs. The higher the speed and the distance, the better your cable needs to be. Any splice or tap will severly reduces cable quality and possible speed and distance.

Gigabit (1000BASE-T) actually works on four-pair Cat.3 but only over a very short distance (a few meters). Fast Ethernet (100BASE-TX) requires only two pairs and is much more lenient, I used a 15+ m run of Cat.3 for a while without problems. 10 Mbit Ethernet (10BASE-T) runs over close to everything for a few dozen or even more than a hundred meters.

Note that Ethernet ports don't automatically link at a lower speed when the cable is sub-standard, you need to configure the ports down. If you do so, do it on both sides or auto configuration will fail and may easily cause a duplex mismatch.

Also note that you can't run a productive link over such a cable without very close monitoring of the error rate.


For ethernet, you need at least 2 pairs of copper wires. Either one of your cables should have that, so you shouldn't need to use two cables. If your cable is indeed cat3, it should support 10BASE-T Ethernet, which would give you 10 MB/s.

If you want to try, you'll need the rj45 connectors and a crimping tool. Then connect both ends using the four wires on the pins 1, 2, 3 and 6 (the numbers should be printed on the rj45 connector or on the manual for that) and you are ready to try it out.


I spoke with Rob Ryan one time. He had Ascend Communications and has a small ranch near here. He told me that Ethernet is pretty resilient and you can get away with a lot, including violating the distance rule (ethernet between the house and the ranch office is way beyond the maximum distance...).

I'm curious if you try two different cables, due to 2 pairs not being in the same cable so we don't have to worry about crosstalk between the pairs. Pin it out so TX and RX are on different cables. Depending on length and other EMI, you might be able to get higher speed, maybe even Gigabit. In a pinch, I'd give it a go if you can't pull in a length of Cat-6.


Well. You can run Ethernet over at least 2 pairs of copper wires. Cat3 UTP was used for 10BASE-T Ethernet, and can carry data up to 10 Mbit/s. If you want to get higher speed, cat 5e or cat6 is recommended (https://www.fs.com/c/cat5e-patch-cables-593). The price is very reasonable. And right now cat3 is rarely used.

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