In the absence of fibre broadband (superfast) services, you will generally be reliant upon ADSL technology (or the more modern ADSL2 or ADSL2+ technology) for the delivery of your broadband service.
ADSL2 and ADSL2+ are enhancements to the original ADSL technology and can provide higher speeds, particularly for those that live close to the BT exchange, as shown in the figure below. The term ‘ADSL2+’ is often used on its own, but equipment capable of supporting ADSL2+ will also support ADSL2.
The key difference between ADSL2 and ADSL2+ is that ADSL2+ uses twice as much bandwidth along copper wires as ADSL2 does. ADSL2 uses exactly the same bandwidth as ADSL. Usually, equipment in the exchange decides on the operating mode to use, with ADSL2+ giving the highest speeds (due to its wider bandwidth) although this makes it more susceptible to line problems. If reliable operation at the wider bandwidth is not possible, the exchange equipment may force operation using the ADSL2 mode. ADSL2+ is generally the preferred mode of operation for shorter distances (from the exchange) and ADSL2 is generally the preferred mode of operation for longer distances.
Users with a line loss of over 55 dB (which corresponds to a distance from the exchange of about 4 km) will generally benefit, as detailed in our Chart of ADSL and ADSL2+ speed versus distance and Chart of ADSL and ADSL2+ speed versus line loss articles.
Chart of ADSL2/2+ and ADSL connection speed against distance from the exchange
Chart of ADSL2/2+ and ADSL connection speed against line loss
The biggest gains from ADSL2+ are achieved for broadband users located close to a BT exchange (principally due to the wider bandwidth being used with ADSL2+). For example, if you are located about 2 km from your exchange (corresponding to a line loss of about 28 dB), you could expect to double your downlink connection speed, from 8.0Mbps (ADSL) to 16.2Mbps (ADSL2+). While more distant users will not experience the same gains in absolute speeds, improvements can still be worthwhile. For example, a relatively distant user located 3 km from the exchange, and currently achieving 6.9Mbps with ADSL, could increase downlink speeds to 9.0Mbps with ADSL2+.
There may be a number of way in which you can get ADSL2+ services, which are now described.
BT has rolled out ADSL2+ services to over 92% of UK premises
According to BT, 99% of homes and businesses in the UK have access ‘first generation’ ADSL broadband.
Over the last few years, BT has been upgrading its exchange equipment from ADSL to equipment capable of supporting ADSL2+ (also known as ’21CN’). In February 2013, BT announced that it would extend ADSL2+ coverage beyond its previous targets and into more rural areas to reach over 92% of UK premises by summer 2013. In February 2015, BT informed ISPs that it intended to upgrade older exchanges to ADSL2+, increasing the penetration of ADSL2+ yet further.
To find out whether your exchange is currently enabled with ADSL2+, you can enter your telephone number or postcode into the SamKnows UK exchange search. Under BT Wholesale information, you will see ’21CN WBC status’. If this is ‘Enabled’, then you already have ADSL2+.
Just because you are connected to a BT exchange that has ADSL2+ capability does not mean that you are automatically connected to the ADSL2+ equipment, so you should contact your ISP to check. We recommend that you migrate to an ADSL2+ service if possible to maximise your connection speeds. Migration from ADSL to ADSL2+ could possibly incur a small charge.
Local Loop Unbundled (LLU) services can offer speed improvements if BT does not currently offer ADSL2+ services
Local Loop Unbundling is the process whereby other operators (such as TalkTalk and Sky) place their own equipment in BT exchanges so that they can offer their own services with more control. LLU services use ADSL2+ technology so can offer superior speeds in exchanges where BT-based services only use ADSL technology.
If BT has not upgraded your exchange yet, then please strongly consider unbundled services if they are available from your exchange. You can check to see if LLU services are available from your exchange by entering your telephone number or postcode into the following:
If BT ADSL2+ or LLU services are not available from your exchange, you will have to rely on basic ADSL technology. However, as described in our Increase Broadband Speed Guide, there are many things you can do to improve your broadband speeds.