Broadband speeds are getting faster for some
BT Broadband is boosting the speeds of millions of its customers to up to 20 megabits per second at no extra cost.
The rollout is part of the firm's planned upgrade of lines to so-called ADSL2+ technology.
The firm said the rollout would start with 40% of the UK this summer and reach 55% of customers by March 2010.
Existing customers will have to sign a new 12-month contract to get the boost, while throttling of video streams in peak hours for some customers remains.
Earlier this week BT was criticised when it was revealed it cut the speed of customers on its cheapest broadband package to below 1Mbps in peak hours when using services like the iPlayer and YouTube.
That so-called traffic management will remain in place with the new speeds.
Download caps for the cheapest two packages, of 10 gigabytes and 20 gigabytes, will also continue, the firm said.
In a statement, Gavin Patterson, chief executive officer, BT Retail, said: "Unlike other providers, BT is upgrading customers to 20Mb/s for free. High-speed broadband provides a faster and more reliable service that will transform the way we live, work, learn and play."
BT said it was starting trials of its fibre optic 40Mbps service in Whitchurch, South Wales and Muswell Hill, London this summer, with the aim of offering these speeds to 40% of the country in the future.
The speed boost to 20Mbps is less than the firm's originally stated aims of offering up to 24Mbps.
On its website, BT says in tests "we've found that only a tiny number of customers can actually get 24Mb".