Using Phone Wiring for Networking?

Here’s a quick one, ever thought of taking some existing phone extension wiring and converting for use in ethernet networking?

Since moving in I’ve had an analogue phone extension socket in the bedroom. The cable runs outside and down the side of the house, before returning into the house close to the BT master socket. It was connected, but was immediately removed to get the best internet speed at the master.

It has 3 pairs of copper, one pair short of what is needed for traditional Cat5 cable, but it is feasible to get 100Mbps from just 2 pairs, all I need to physically connect my Raspberry Pi media player in the bedroom to my network.

There’s nothing wrong with connecting it up, right?

The old phone socket (library photo)

When moving in I’d cut the connection to the master socket close to its entry back into the home, so to reinstate a RJ45 end was added, using two pairs connected on pins x and x on the first, x and x on the second. The extension end was terminated into a new standard RJ45 socket.

A coupler and patch cable completed the connection to the switch at the master end, and a laptop connected at extension end to perform some tests.

First sign that this wasn’t a robust solution, the laptop displayed a connect/disconnect loop around 5 or 6 times, before settling on a 10Mbps link speed to the Gigabit switch.

Game over already, with a sync of 10Mbps it may support a video stream under 1.25MBps, below the requirements of HD video and so denying me of most of my TV library.

As an exercise, how does this phone wire perform as 10Base-T?

A speed test looks as expected, getting close to the 10Mbps established line speed.

A constant ping from behind the wire shows the saturation, along with the oddity that the upload test appears less loaded than download, even though my connection can easily saturate this connection.

What’s very apparent are ping timeouts throughout all stages of the test, evidence that this is not a happy nor reliable connection.

In conclusion, yes you technically can use old phone cabling as ethernet, just don’t expect to put any reliable or modern day traffic through it.