Cable vs full fibre: why your street only gets one of them

Two neighbours on the same street can be entitled to completely different broadband, at different prices, from providers that do not compete with each other. This is not a glitch. It is the result of how the UK's networks were built, and of an economic calculation that is made street by street rather than nationally.

Understanding which network you are on explains most of the things that otherwise look irrational about broadband pricing: why one provider offers 1,130 Mbps and another tops out at 76, why moving 200 metres changes your options, and why the cheapest deal is sometimes on the slower line.

There are three network types in the UK: part-fibre (FTTC), cable, and full fibre (FTTP). FTTC reuses the old copper phone line for the last stretch and typically delivers 36–76 Mbps. Cable uses coaxial cable and reaches beyond 1 Gbps. Full fibre runs fibre all the way to your home and is the most reliable of the three. Which you can get depends on what was physically built on your street, not on which provider you prefer.

The three networks, plainly

Almost every UK connection is one of these, and the difference that matters is how far the fibre runs before it turns into something older.

• Part-fibre (FTTC). Fibre runs from the exchange to a green cabinet on your street, then the existing copper phone line carries the signal the last few hundred metres to your home. This is the majority of the country. It is capable of 36–76 Mbps downstream, with upload speeds roughly a tenth of that. Distance from the cabinet matters enormously: the further you are, the slower it gets.
• Cable (HFC). A separate network built with coaxial cable, sharing fibre back to the headend. It does not use the phone line at all, which is why cable customers historically did not need a landline. Downstream capacity is high — gigabit tiers are routine — but the network is shared with your neighbours, so peak-time performance depends on local congestion.
• Full fibre (FTTP). Fibre runs all the way into your home, terminating at an optical unit on the wall. No copper, no distance penalty, no sharing at the cabinet. Speed tiers from 100 Mbps to multi-gigabit, upload speeds much closer to download, and lower latency than either of the others.

What it means in ordinary use

For browsing and streaming, all three are adequate. A 4K stream needs about 25 Mbps, so even the slowest FTTC line handles two of them at once. The differences show up in specific situations.

Why the differences are felt on upload, not download

Download speed is what gets advertised, but upload is where old networks show their age. On a part-fibre line the upload is typically 5–20 Mbps, which is fine for browsing and marginal for a household where two people are on video calls and a third is backing up to cloud storage.

This is the single most common reason people on FTTC upgrade and then feel no difference: they bought more download and their problem was upload. If your calls freeze, your files take hours to sync, or your security cameras drop out, check the upload figure before you buy a faster download tier.

Why your street only gets one

Building fibre is expensive and the cost is almost entirely fixed per street: digging, ducting, permits, and connecting every property whether or not they buy. The revenue, by contrast, depends on how many households on that street actually sign up. That ratio decides whether a build happens.

This produces the pattern you see in practice. Dense urban streets with high churn get built first, sometimes by two or three competing networks. Rural areas with long driveways and low take-up may wait years, or be served only by a subsidised rollout. A new-build estate gets full fibre because it is cheaper to install during construction than to retrofit.

It also explains why 'we cover your area' and 'we cover your address' are different claims. Coverage maps are drawn at postcode level and are frequently wrong at the individual property.

How to find out what you actually have

• Check the router. If it plugs into a standard phone socket, you are on part-fibre. If it connects to a coaxial wall point, you are on cable. If a small optical box is mounted on the wall with a fibre lead running into the router, you have full fibre.
• Look at the cabinet. A green street cabinet within a few hundred metres usually means FTTC; that distance is why your speed may be lower than your neighbour's.
• Run a speed test twice, once wired and once over WiFi, at a quiet time of day. A wired result close to the advertised figure with a much lower WiFi figure points to a WiFi problem, not a network one.
• Check at address level, not postcode level. The Ofcom coverage checker reports what every operator can deliver at a specific address, which is more reliable than the marketing pages of providers selling over the network.

The copper switch-off matters here

The old telephone network that part-fibre depends on for its final stretch is being retired, with the process planned to complete in the late 2020s. Once it goes, the copper path stops working entirely: FTTC customers have to move to a fibre-based service, and traditional landline phones stop functioning without a digital replacement.

In practice this means the choice you have today is temporary. If you are on part-fibre and full fibre is available at your address, taking it now avoids being forced to migrate at a moment you did not choose. If full fibre is not available yet, it is worth checking annually rather than assuming nothing has changed.