How does fibre optic broadband work?

Fibre optics


I’m thinking about switching to fibre optic broadband, but I don’t really understand it all. How does fibre work? And should I get it?


Our expert Kim says...

Fibre optic broadband, as you probably already know, is broadband that gives you superfast speeds and enough bandwidth to get loads of gadgets online at once. It's good stuff.

The majority of UK broadband providers have fibre packages - but with some of the jargon the industry uses, it can definitely get confusing when you try and figure out exactly what you need. So let's unpack it all and take a look.

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What is fibre optic broadband and how does it work?

Fibre broadband is all in the cables.

The lines that deliver fibre broadband do indeed consist of fibre optics - yes, exactly like those cool hippy lamps. The cables involve tiny tubes, each about as thick as a human hair, that are reflective on the inside. They transfer information by sending flashes of light through the tubes, which bounce off the inner walls to travel along the cable. Equipment at the receiving end can then interpret the flashes as data.

Fibre optic cable

Because the data is travelling at literally the speed of light, it means very fast broadband speeds for you. Generally, you'll find fibre broadband available with average speeds of 35Mb, 57Mb or 63Mb, though some providers can offer packages with average speeds of 350Mb and above or even 1Gb (1,000Mb).

Fixed line broadband that isn't fibre optic is called ADSL (asymmetric digital subscriber line). Data is instead sent through the traditional copper phone lines all the way from the exchange, and it's usually available with average speeds of 17Mb.

Does fibre optic broadband use a phone line?

Yes, it does.

Although the majority of your broadband connection would be fibre optic, the bit between your local street cabinet and your home is still the old copper phone line. That's why line rental is almost always included in a broadband package.

Virgin Media is an exception to that though, since it uses its own kind of cables.

Switching to fibre

If fibre optic broadband is available in your postcode, switching to it is easier than you may think. All you need to do is choose a package and sign up.

Can I get fibre broadband?

If your home's never had a fibre connection before, an engineer may need to visit to install the right equipment in your phone socket - but that's the extent of any hassle, and it's done at no extra cost to you.

Once your home has an appropriate socket, all you need to do is plug in your new router and wait for the new fibre service to go live.

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Fibre-to-the-cabinet (FTTC) vs. fibre-to-the-home (FTTH)

Fibre-to-the-cabinet (FTTC) is the most common setup for fibre broadband. Fibre cables run from the exchange to the cabinet on your street, which then connects to your home via the ol' copper phone line.

This is the kind of fibre broadband you'll get from Openreach-based providers, including BT, Sky, TalkTalk, Plusnet, Vodafone, and EE.

Fibre-to-the-home (FTTH), meanwhile, means the entire line is fibre from the exchange all the way into your building. It allows for even faster speeds, but is only available in precious few places - and can be very difficult and expensive to install. BT offers FTTH connections in certain circumstances, and you'll find packages available from niche providers too.

It can also be known as FTTP (fibre-to-the-premises) or FTTB (fibre-to-the-building).


Again, one provider that works a bit differently is Virgin Media. If you have Virgin Media broadband, the lines between the exchange and your street cabinet are fibre optic, but between the cabinet and your home is a coaxial cable. Although they're mostly made of copper, coaxial cables can send data way faster than standard phone lines. That's how Virgin Media can offer average speeds of 362Mb.

Do I need fibre broadband?

Fibre broadband is a very useful thing to have, as it's much faster and a lot more reliable than ADSL. It means more devices can connect at once and still get decent speeds, videos barely buffer at all, and files download nice and quickly.

On the downside, it's more expensive than ADSL - and it's not available everywhere. It also takes longer to install and go live in the first place, especially if your home hasn't had a fibre connection before.

We recommend getting fibre if…

  • You have a large household - say, three or more people
  • Lots of gadgets in your home are connected to the internet - remember that computers, smartphones, tablets, smart TVs, and games consoles all use broadband
  • You like to watch videos, streaming sites like Netflix, or catch-up TV
  • You're a gamer
  • You work from home and need to download important files or connect to a VPN

Or if you just want superfast speeds when you use the 'net, of course.

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