What is VDSL?

VDSL stands for Very High Speed Digital Subscriber line. In the UK, the most common standard is VDSL2 connected via FTTC, often on a BT Openreach subscription, although other telephony firms using the cable network infrastructure include EE and Plusnet.

FTTC stands for Fibre-To-The-Cabinet. This means that the street cabinet nearest to you is connected to the telephone exchange with fibre optic cable, but your connection to the cabinet still uses old-school copper telephone wiring, which is slower but means that existing infrastructure can be used for faster internet connections. This last leg of the journey is frequently referred to as a copper last mile.

The fastest VDSL2 VPlus (Annex Q) connections have a theoretical maximum download speed of 300 Mbit/s and a maximum upload speed of 100Mbit/s, but older deployments that haven’t let been upgraded have a slower upper threshold and are slower still in actual deployments.

Average download speeds for UK VDSL2 FTTC connections are 42.6 Mbit/s, but there are strong disparities between speeds in urban and rural areas – the longer the copper cable run it, the slower your internet connection will be. The fastest average upload speed for an FFTC VDSL connection was around 16Mbit/s in 2021.

By comparison full fibre (FTTP, or Fibre-To-The-Premises) connections averaged 145.4Mibt/s download speeds, and cable connections (on fibre optic cable infrastructure from an independent provider such as Virgin Media) averaged 111.1Mbit/s but peaked at download speeds of 490.3 Mbit/s, depending on subscriber package. Neither Virgin Media cable nor BT’s full fibre offerings use VDSL, but instead use rebranded fibre or cable modems from reliable manufacturers.

VDSL modems and modem-routers are distinct in that, in the UK, they still use a standard RJ11 cable to that goes from a normal telephone wall socket to the back of your router or modem.

You can often shop around for your choice of VDSL modem routers. In cable and full fibre installations, you’ll generally have a dedicated connection box, which you can then attach a standard modemless network router to.

Upgrades are under way across the UK to increase coverage of fibre networks, which should see more business and consumer subscribers receiving full fibre connections. You can use Ofcom’s Mobile and broadband checker to see what speeds are available for your address.

Data in this explainer is taken from Ofcom’s 2021 Online Nation Report and Broadband Speeds Research.