BT customers will begin to enjoy the result of its much delayed 21CN network upgrade as it today begins to convert its retail broadband offering nationwide to ADSL2+, which will offer speeds of "up to" 20Mbit/s.

In reality, most homes and businesses are likely to see a small improvement on whatever their current "up to" 8Mbit/s service offers. There will be no extra charges for the faster lines, BT said. Download caps and application throttling will remain in place.

CEO Gavin Patterson announced the upgrade with a dig at main rival Virgin Media, whose 20Mbit/s and 50Mbit/s services cost significantly more than its slower packages.

"Unlike other providers, BT is upgrading customers to 20Mb/s for free," he said.

"High-speed broadband provides a faster and more reliable service that will transform the way we live, work, learn and play. We are already the UK's largest retailer of broadband and today's announcement shows that we offer terrific value for money."

BT has been trialling ADSL2+ with about 60,00 customers. Its wholesale division has meanwhile allowed several resellers to offer ADSL2+ for many months.

As part of the launch of ADSL2+, BT said it would give away its "BT Broadband Accelerator", a device to reduce line interfence, to homes and businesses likely to benefit.

BT trials of fibre to the cabinet technology, which will downstream offer speeds of up to 40Mbit/s, will begin this summer in Muswell Hill in London and Whitchurch in South Glamorgan. The firm plans to roll the technology out across 40 per cent of its network by 2012. ®

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