British Telecom has launched a trial of its public wireless broadband network, ahead of its commercial launch on 1 August.

BT plans to build a national network of access points around key public sites, such as hotels, airports, bars and coffee shops - all within reach of business travellers and commuters.

The so-called wireless local area network (LAN) will allow people with a laptop and a wireless LAN PC card to send and receive data at broadband speed - as long as they are close to one of these "hotspots".

On Monday, three BT hotspots went live at the Heathrow Hilton, the BT Centre in London and the BT development centre in Suffolk.

BT has agreed deals with Hilton Hotels, Bluewater and Earl's Court Olympia and up to 20 hotspots will be operational by 1 August.

About 70 are set to be in place by December this year.

How much?

BT hopes to have 4,000 hotspots in place by June 2005.

By then, it hopes to be generating revenues of at least �30m ($45m) a year from the service.

Demand for the service will depend on pricing. BT plans to offer access through subscription or pay-as-you-go.

So far, BT suggests that customers will pay less than �95 a month for continuous use. Early subscribers could have a discount of up to 50%.

BT says it is too early to say what the charges for occasional users will be.

Looking for 'hotspots'

Wireless broadband access depends on the installation of these "hotspots".

Within 100 metres of such wireless hotspots, people with a mobile device, the right network card and the right software, will be able to use their devices to access data.

The wireless LAN will be developed in conjunction with Cisco Systems and Motorola.

About 100 Motorola staff will be involved in the pilot scheme.