- ADSL runs entirely over the copper telephone line and was the first mass-market broadband technology in the UK.
- Standard ADSL offers download speeds up to around 8 Mbit/s, while ADSL2+ raises the theoretical maximum to around 24 Mbit/s.
- ADSL speed falls with distance from the telephone exchange, because the copper signal weakens (attenuates) over longer lines.
- Openreach is retiring copper-based products through a programme of stop-sell milestones as full fibre is built out across exchange areas.
- Openreach plans to switch off the analogue PSTN telephone network around the end of January 2027, accelerating the move away from copper.
ADSL is broadband delivered over the copper phone line. Speeds depend heavily on distance from the exchange, peak at around 24 Mbit/s on ADSL2+, and are being retired by Openreach in favour of fibre.
Last reviewed: June 2026
How ADSL works
ADSL stands for Asymmetric Digital Subscriber Line. It carries internet data over the same copper pair that delivers a traditional telephone service, using frequencies above those used for voice. A microfilter at each socket separates the two so that calls and data can run at the same time without interference. The signal travels from the home along the copper line to the local telephone exchange, where equipment connects it to the wider network.
The asymmetric part of the name reflects the design. ADSL gives a much higher download speed than upload speed, on the assumption that most households receive far more data than they send. That assumption made sense when the technology launched, although heavier use of video calling and cloud backup has since made upload speed more important than it once was.
Why distance from the exchange matters
The single biggest factor in ADSL performance is how far the property sits from its exchange along the copper route. Electrical signals weaken as they travel over copper, an effect called attenuation. A home close to the exchange may see speeds near the technical maximum, while a home several kilometres away on a long line can see speeds drop to a small fraction of that. The quality and age of the copper, joints in the line and internal wiring all add to the loss.
This distance sensitivity is why two neighbours on different line routes, or two homes in the same village at different ends, can record very different ADSL speeds despite paying for the same package. It is also a core reason the UK moved towards fibre, which does not suffer the same distance penalty.
ADSL versus ADSL2+
The original ADSL standard offered download speeds up to around 8 Mbit/s. ADSL2+ improved on this by using a wider band of frequencies on the copper line, raising the theoretical maximum to around 24 Mbit/s for homes close to the exchange. Upload speeds also improved modestly. In practice, the headline figures are rarely reached on longer lines, and the real benefit of ADSL2+ is mainly felt by properties near their exchange.
| Line length from exchange | ADSL typical download | ADSL2+ typical download |
|---|---|---|
| Very short (under 0.5 km) | Up to about 8 Mbit/s | Up to about 24 Mbit/s |
| Medium (around 2 km) | About 4 to 6 Mbit/s | About 10 to 16 Mbit/s |
| Long (around 4 km) | About 1 to 3 Mbit/s | About 3 to 7 Mbit/s |
| Very long (over 5 km) | Under 1 Mbit/s possible | Under 3 Mbit/s possible |
Who still has ADSL
ADSL remains in service mainly where faster options have not yet been built, or where a household has not switched to an available alternative. As Openreach extends fibre to the cabinet and full fibre across the country, the number of homes relying on ADSL has fallen sharply. Some rural and harder-to-reach properties continue to depend on it while fibre rollout reaches them.
For these households, the practical effect is a connection that can struggle with modern demands such as multiple 4K streams, large simultaneous downloads and several people working from home at once. The technology still functions, but it was designed for an earlier pattern of internet use.
The phase-out of copper broadband
Openreach is retiring its copper-based products as full fibre becomes available in an exchange area. This happens through stop-sell milestones, after which new copper-based orders, including ADSL, can no longer be placed in that area and customers move to fibre instead. Separately, the analogue telephone network is being withdrawn, with the switch-off scheduled around the end of January 2027. Voice services are moving to digital connections, which removes a key reason for keeping the copper voice line that ADSL depends on.
For most homes the change means a move to FTTC, SOGEA or full fibre. The timing depends on local rollout, and providers contact affected customers ahead of any change to their service.
Can ADSL be upgraded
Where a faster product is available at the address, moving from ADSL is usually a matter of ordering the new service rather than any physical upgrade to the existing copper. FTTC reuses part of the existing line, while full fibre involves a new fibre connection into the property. An availability check against the Openreach or Ofcom databases shows which options serve a given address.
For households still on ADSL, it is worth checking availability periodically, because rollout changes the picture over time. An address that had no fibre option a year earlier may since have been passed by an Openreach build or by an independent network. Where nothing faster has yet reached the property, the broadband Universal Service Obligation may provide a route to a connection of at least 10 Mbit/s download and 1 Mbit/s upload, subject to eligibility and the cost rules set out by gov.uk and Ofcom.
Living with an ADSL connection
While a property remains on ADSL, a few practical points help the line perform as well as it can. Internal wiring, extension sockets and old microfilters can all reduce the achievable speed, so connecting the router at the master socket and using a good filter can make a measurable difference on a marginal line. Reducing the number of devices competing for a small amount of bandwidth, and scheduling large downloads for quieter times, also eases the strain on a slow connection.
None of this changes the underlying limit set by the copper distance, but it can recover speed that poor internal setup has lost. The longer-term answer for most homes remains the move to fibre as it becomes available, which removes the distance penalty that defines the ADSL experience.
It is also worth knowing why ADSL behaves the way it does compared with newer products. The copper pair was designed to carry a telephone call, not high-speed data, so squeezing broadband onto it was always a compromise. The signal shares the line with electrical noise from nearby wiring and appliances, and the modem constantly adjusts to keep the connection stable, sometimes trading speed for reliability. This is why an ADSL line can quietly slow down over time as conditions change, and why the speed shown on a router can differ from a one-off test. Recognising these traits helps set realistic expectations for a connection that, while now dated, still keeps many properties online while fibre rollout reaches them.
Frequently Asked Questions
How fast is ADSL broadband?
Standard ADSL offers download speeds up to around 8 Mbit/s, while ADSL2+ can reach around 24 Mbit/s for homes close to the exchange. Real-world speeds are usually lower and fall with distance from the exchange, so many ADSL lines deliver well below the headline figure.
Is ADSL being switched off?
Openreach is retiring copper-based products through stop-sell milestones as full fibre is built out, and the analogue telephone network is scheduled to be switched off around the end of January 2027. ADSL is being replaced by fibre-based services as a result.
Can ADSL be upgraded to fibre?
Where fibre to the cabinet or full fibre is available at the address, moving off ADSL is a matter of ordering the new service. Full fibre involves a new fibre line into the property, which an engineer installs. An availability check shows which options serve a given address.
What is ADSL2+?
ADSL2+ is an improved version of ADSL that uses a wider band of frequencies on the copper line to raise the theoretical maximum download speed to around 24 Mbit/s. The gain is mainly felt by homes close to the exchange, as the benefit reduces with distance.
How does distance from the exchange affect ADSL speed?
ADSL signals weaken as they travel over copper, an effect called attenuation. The further a property is from its exchange along the line route, the lower the achievable speed. This is why homes on long rural lines often see only a fraction of the headline ADSL speed.
