Fibre Broadband in the UK: Full Fibre Against Fibre to the Cabinet

Fibre broadband is two products sharing a word. One brings fibre all the way to the building. The other brings it to a green cabinet in the street and finishes the journey on the copper phone line that was already there. They are advertised almost identically and they do not behave alike.

The two things called fibre

Fibre to the cabinet, usually shortened to FTTC, is the older arrangement. The fibre reaches a cabinet serving your area and the last stretch to your door is copper. Because copper degrades over distance, your speed depends on how far you are from that cabinet, which is why two houses on the same tier and the same street can measure differently and both be working as sold.

Full fibre, or fibre to the premises, runs fibre to the wall of the building. There is no copper leg, so distance from the exchange stops being the limiting factor, and the connection is either symmetric or close to it.

The wording to look for on an order page is full fibre or fibre to the premises. Fibre broadband on its own, or a tier name with fibre in it, does not tell you which of the two you are buying.

Why upload is the difference that matters

Download figures on FTTC are respectable and have been for years. Upload figures are not, and upload is what has changed in how households use a connection.

Video calls consume upload. So does cloud backup, sending large files, uploading video, and any camera that streams offsite. A household doing several of those at once can exhaust a modest upload allocation while barely touching the download figure printed on the bill.

That is the mechanism behind the most common broadband complaint that is not a fault: the speed test looks fine, and the video call stutters anyway. The test measures download; the call needs upload.

Who builds full fibre in the UK

Openreach is the incumbent network and the one most retail brands rent: BT, EE, Sky, TalkTalk, Plusnet, NOW and others all sell over it. Its full-fibre build has been extending steadily, so availability at an address changes over time.

CityFibre is the second largest wholesale full-fibre builder and the main national alternative, concentrated in mid-sized towns and cities. Several retailers sell over it, including Vodafone and TalkTalk, which is why the same brand can mean different technology at different addresses.

Virgin Media is a separate case: its own cable network, not rented from anyone, delivering large download figures with much smaller upload. And smaller regional builders exist in individual towns, sometimes with the best product available locally.

Checking what you can actually get

Check by address, not by postcode and definitely not by town. Network builds stop mid-street routinely, so a neighbour having full fibre is suggestive rather than conclusive.

Re-check if it has been six months. In an active build area the answer changes, and a negative result from last year is not a negative result now. It costs nothing to look again.

Then establish what the installation involves. Moving to full fibre on a network that has not served the property before is a physical job, someone digs or pulls a cable, and a small box goes on an internal wall, which needs an appointment and, in rented accommodation, may need the landlord's agreement.

What full fibre will not fix

Wi-Fi. A fast line into a router that cannot get a signal through two solid walls produces the same complaint as a slow line, and upgrading the line does nothing about it. If the problem is worse in one room than another, the problem is not the line.

Device limits are the other one. An older laptop or a cheap smart TV may not be capable of the speeds you are paying for, so the tier above the one you need buys nothing at all.

And moving up within full fibre rarely changes anything a household notices. The step that matters is copper to fibre; the steps after that are mostly numbers. See the providers, how switching works and broadband without a phone line.

Why the word was allowed to mean both

For most of the last fifteen years UK advertising rules let a part-fibre connection be sold as fibre broadband, on the reasoning that fibre was involved somewhere in the path. That was defensible when almost nothing was full fibre and indefensible once full fibre became widely available, because by then the same word was covering products that differed by an order of magnitude on upload.

The practical residue is that older marketing language survives on comparison sites, in cached pages and in the tier names providers were already using. A package called a fibre tier in 2018 is still called that today, even where the same brand now also sells a genuinely full-fibre product alongside it.

Which is why the useful question at an order page is not what the tier is called. It is what reaches the building: fibre, or copper carrying the last hundred metres. Ask it in those terms and the answer is unambiguous, whatever the marketing says.

Frequently asked questions