BT has promised 8Mbit/s broadband across the UK by next spring.
Testing will start at 25 exchanges next month, the monster telco said, that will "lay the foundation for the intended commercial launch of higher speed broadband services across the UK by Spring 2006".
MD of products and strategy at BT Wholesale, Cameron Rejali, said: "This trial phase is essential to ensure our higher speed broadband products and systems meet the reliability standards that service providers and end users expect. BT is committed to ensuring that everyone benefits from the broadband revolution whether they live in valleys, villages or city centers."
Following successful trials in London and Strathclyde, the wider trial phase will eventually rise to 53 exchanges. Exchanges named are in Greater London, Cornwall, Strathclyde, Northern Ireland and South Glamorgan.
The trial will initially be available to 50,000 end users. Individual customer lines for the trial will be selected by service providers.