Convert RJ11 to RJ45

Question

I have random RJ11 wires in house which have been cut off as they were used for the master socket and the master socket was in an awkward place. And I was wondering if it was possible to convert both ends of that cable into a RJ45 cable to connect to my PS4 from the router saving time and money from having to buy and install a new cable.

Edit: I don't think it's a "cat" cable. It doesn't have any writings at all. It's the cable used in UK for the master socket (BT 5C) to connect it to the phone and router. Not sure if it's different in other countries. Just a thin white cable. Thinner than a standard RJ45 Cable. –

Is this possible?

Solution

The answer is possibly... but without knowing more about the cable and the layout it is difficult to tell.

In theory, telephony cable can be used to support 10/100 connections (not Gigabit) over short distances. If you can find a telephony cable that is not cut and is a "home run" between the two points you need to connect, and it contains at least 4 conductors, it may be possible.

For 10/100 Ethernet to work, you need to have a straight through connection of pins 1, 2, 3, and 6, and the other pins are not relevant/not used in this scenario.

For the purposes of this, we will say the cable has Red, Green, Yellow, and Black conductors. They may be different colored or contain more conductors, but this is all we are concerned with. If the cable is solid with a matching stripe (Blue with a white stripe and white with a blue stripe twisted together, even better).

Connect both ends of the cable the same to an RJ45 JACK (do not crimp ends on the cable), essentially we are going to substitute color pairs of the existing cable for "standard" color codes in EIA/TIA 568B color code.

In the 568B color code, we need W/O-O/W (Pins 1&2) and W/G-G/W pairs (Pins 3&6) Pins 4, 5, 7, and 8 can be ignored (they are for PoE and Gigabit applications, which we are not going attempt with this type of cable).

Now substitute... If you cable is Red/Green Yellow/Black, connect the green to Pin 1, the Red to pin 2, the black to pin 3 and the yellow to pin 6, do the same on both ends and connect with a standard patch cable to the router and computer. If the color are different, just substitute as necessary.

Now, the reality this might work perfectly at 100Mbps, or it may error out like crazy... it may function fine at 10Mbps or fail just as miserably... Or it may not link up at all. There is no way of knowing until you try it.

Comments

[Tyson]

Doubtful, but what is the cable type? Read the printing on the wire jacket look for the word Cat and tell us what number follows that word.

[ToysonGrape]

I don't think it's a "cat" cable. It doesn't have any writings at all. It's the cable used in UK for the master socket (BT 5C) to connect it to the phone and router. Not sure if it's different in other countries. Just a thin white cable. Thinner than a standard RJ45 Cable.

[Tyson]

You might want to edit those details into the question.

[Appleoddity]

Having existing cable makes it much easier to pull new cable so that you can just do it properly. I can tell you right now you’re gonna throw this idea out the window as soon as your video games start glitching in the heat of a battle.

[Baldrickk]

As @Appleoddity says, best use of that existing cable is to pull a new cable through.

[ToysonGrape]

If I remember correctly i think had four cables but i might be wrong need to check when i get time tomorrow.

[Zina]

nice detailed answer. in reality I have done this and it worked. of course it depends of the state the cables are in. if those cables are there for a long time it might not work. a lot of times bad wires would cause troubles for ADSL routers and low speeds or disconnects. and dont forget it might be a 2 wire cable (the 4P2C ones, against the 4P4C ones).