Telewest is investing £20m in its PVR technology, which follows in the steps of BSkyB's personal video recorder service Sky+.
BBC Worldwide will initially provide more than 180 hours of programming including documentaries, natural history, children's programmes, drama and light entertainment. Discovery will provide a similar mix of factual and lifestyle programming from its network of channels.
The media group has already secured contracts with FilmFlex, the BBC, Nickelodeon and several adult channels, with negotiations for other programmes taking place.
The service is due to launch in Bristol at the start of July and will be made available region by region throughout the second half of the year. The company is aiming to give more than 1m customers access by early 2006.
Eric Tveter, president and chief operating officer at Telewest Broadband, said: "We truly believe TV-on-demand will transform the way consumers watch TV.
"We're lining up top-quality content providers to give our customers a superb choice of programmes and the flexibility to watch them whenever they want."
TV-on-demand gives customers instant access to a library of films and TV programmes via the remote control and set top box. It also allows viewers pause-and-rewind live programming as they watch it.
The company has announced a phased analogue switchover programme to turn its remaining 171,000 analogue TV customers to digital by the end of 2006, in line with the analogue switch proposed by the government for 2012.
In May, Telewest increased its subscriber base to 1.8m with revenues growing by 3% to £338m, according to its full-year financial results.
Telewest is currently negotiating with the UK's other cable firm NTL over terms of a £5.6bn merger.
NTL is due to launch a similar PVR service later in the year.
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