July 6, 2022
What is ADSL And How Does it Work?

What is ADSL And How Does it Work?

Read time:
2 Minutes

ADSL is one of the most commonly available forms of broadband—but what is ADSL, how does it work and why is it being switched off?

What is ADSL?

ADSL Stands for Asymmetric Digital Subscriber Line and is a type of broadband connection that is delivered using the UK’s copper telephone network. ADSL is the slowest form of broadband connectivity, with a maximum speed of 8Mbps.

Key features of ADSL

  • Has both voice and data (broadband) delivery capability
  • Uses the copper telephone network
  • Maximum speeds of 8Mbps download
  • Is being phased out by BT for 2025

Introduced in 2000, ADSL is an older technology, and has been swiftly replaced by the newer fibre to the cabinet (FTTC) and fibre to the premises (FTTP) broadband. As you would expect, fibre is much faster and offers higher bandwidth to homes and businesses.

Fibre Broadband
Fibre is the replacement for ADSL

What is ADSL2/2+

As its name suggests, ADSL2/2+ are the successors to ADSL, providing higher bandwidth and speeds. The maximum speeds achievable on ADSL2/2+ are 24Mbps download. 

Although ADSL2/2+ uses the same copper infrastructure and lines, it uses a different protocol and software technology to achieve higher speeds. ADSL2/2+ is a direct replacement for standard ADSL.

How Does ADSL Work?

An ADSL broadband line uses the copper connection between your premises and the local telephone exchange to send and receive voice and data signals. The UK is littered with green street cabinets, which are the middle man between premises and the telephone exchange.

ADSL Diagram
ADSL Diagram

If you have ADSL broadband, you’ll have a device called a DSL filter (sometimes called a splitter), which isolates the broadband and voice spectrums, allowing you to send and receive both using the same copper line.

How Fast Is ADSL Broadband?

The speeds your premise receives from ADSL highly depend on the distance from the cabinet/exchange. The further away from the cabinet you are, the slower the speeds.

Most businesses or homes with ADSL receive nowhere near the maximum speeds, due to the high impedance of copper lines—which means that the broadband signal drops off quite quickly.

This diagram below shows the speed comparison drop off the further you are from the exchange/cabinet.

ADSL vs ADSL2+ Speed Comparison
ADSL vs ADSL2+ Speed Comparison

Data provided by increase broadband speed

Is ADSL Being Turned Off?

In 2025, BT and Openreach, who manage the vast majority of the UK’s copper and ADSL network, are turning off ADSL. This is commonly referred to as the ISDN switch off.

As we said before, ADSL is an old technology and much slower than it’s modern counterparts. In 2019, Openreach took the decision to switch off the ADSL and ISDN networks.

What Are The ADSL Alternatives?

With the 2025 ADSL switch off looming, here are a few alternatives to ADSL broadband, they are:

Fibre Broadband

Fibre to the cabinet or fibre to the premises is the direct replacement for ADSL, offering more bandwidth, higher speeds and lower latency. However, fibre isn’t available everywhere, and chances are if you haven’t upgraded to fibre already, it may not be available in your area.

SOTAP Broadband 

SOTAP is a fancy new technology that acts as an intermediate step between ADSL and fibre. It stands for Single Order Transitional Access Product, and uses the exact same copper lines, which means that your address does’t need to have fibre installed to access SOTAP. 

The downside is that SOTAP does not improve your speed, it nearly migrates your service to a platform that is ready for the 2025 switch off.

5G or 4G LTE Broadband

A common alternative to ADSL broadband is using the UK’s 5G or 4G LTE network. This is a great alternative for businesses working in more rural areas that have mobile/4G coverage, but no fibre availability. 

4G and 5G antennas can be used to maximise the speed, and provide a more reliable and faster connection than ADSL. 4G/5G is also ‘2025 switch-off proof’.

Leased Line

A leased line is a direct fibre connection from your premises to the nearest fibre connection (usually an exchange). They have almost no geographic restrictions and can be installed anywhere, even where there is no existing fibre infrastructure. 

Leased lines are usually reserved exclusively for businesses, as they often cost hundreds of pounds a month, and require a physical installation which can involve excess construction charges.

Thinking of upgrading your business from ADSL? Not sure which option is best? Speak with a member of our team for friendly, no obligations advice about your business connectivity and learn about which option is best for you.

If you have any questions, or would like some more information about how Bytes Digital can help your business, email hello@bytesdigital.co.uk give us a call on 03331 301 021.

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