What is ADSL broadband?

Most UK broadband is ADSL, which is part of the DSL family of broadband technologies which use the old copper telephone wires laid decades ago by companies like BT.

Voice telephone calls only use the frequencies that a human can hear, but the copper wires can carry much high frequencies, and DSL uses these for high speed data, while voice calls are unaffected.

Asymmetric DSL – ADSL – squeezes even more data down the line by using most of it for downloads to your home, because most people don’t need to upload very much data if they’re surfing the Web, streaming video or downloading files. Most broadband providers operate a 10:1 ratio of download to upload, so with a 10Mbps service you get 1Mbps uploads (or more likely 500Kbps on a 5Mbps connection).

Symmetrical DSL – SDSL -is available for businesses which run servers and need to upload to their customers as fast as they download.

Coverage

Nearly every copper phone line in the UK can now get ADSL, and 86 per cent get more than 2Mbps. Although the high speed data signal doesn’t travel far over normal telephone cables, providers can now get over this by either installing amplifiers and repeaters along the lines in street cabinets, or by running fibre from the exchange to a street cabinet, so the distance covered over copper wire is shorter.

ADSL requires a DSL modem to connect to the internet, which is typically supplied by your service provider with all their settings pre-installed. Your provider can usually access this if they need to fix a problem or update its firmware. It’s usually has a built-in wireless network router for a home network, which you can access to change your network settings.

DSL users must usually fit plug-in ‘microfilters’ at each phone socket to stop the voice and data signals interfering with each other, although some broadband operators no longer bother with these unless a customer reports a fault.

What to look for:

• How far is my local exchange?
• How fast will my connection be?
• Do I need a fast upload speed?
• What is the download capacity?
• Does it come with a wireless router?