The move to roll out wireless internet technology will threaten the revenues of Britain’s mobile phone operators.

Birmingham, Manchester and Leeds are among eight cities — plus three London boroughs — singled out for the installation of so-called “WiFi hotspots”.

Each hotspot will provide access to the internet for those using a computer without the need for wires. Together, the hotspots will provide blanket coverage of outdoor areas in the city centres.

People in those cities will be able to use laptop or handheld computers to access the internet.

Many mobile phone users will also be able to bypass their mobile phone networks to make inexpensive national and international calls, send e-mails or transfer documents using the new internet networks.

Phones with a WiFi chip can link to wireless internet networks at the touch of a button. There are at present about 25 mobile phone handsets that have WiFi chips installed. However, that number is set to increase rapidly as the technology becomes more widely available.

Most laptop computers now contain a WiFi chip to enable access to the internet without the need for cables.

So far, WiFi zones, where users can access the internet wirelessly, have tended to be in coffee shops, railway stations or office blocks. Philadelphia and San Francisco have both set up city-wide WiFi networks in an attempt to attract and retain high-growth technology companies.

Mobile phone users will be able to use the new networks to make phone calls using internet telephony, or Voice over Internet Protocol (VoIP). At the touch of a button, users will bypass their mobile phone network and connect to the internet using the WiFi-based network instead. The voice is split up into tiny packets of data and carried over the internet as data traffic.

The internet takes no account of geographical distance, making long-distance calls particularly worthwhile.

Internet telephony has been seen largely on desktop computers, where users can make calls using a headset or handset connected to their computer.

Calls between two desktops are free and calls from a desktop to a landline are usually inexpensive. Users of the new WiFi networks will be required to pay access charges to an account provider, such as BT or T-Mobile.

Whereas American projects have tended to be driven by public bodies, this scheme is being developed by The Cloud, a London-based, private equity-backed WiFi firm.

George Polk, chief executive of The Cloud, said that he expects voice calls to represent about a third of revenues.

The networks will be launched in Edinburgh, Leeds, Manchester, Birmingham, Nottingham, Oxford, Cambridge, Liverpool and the London boroughs of Kensington and Chelsea, Camden and Islington.

The network equipment will be installed on street furniture, such as lampposts and street signs. Revenues will be shared between the owners of the furniture on which equipment is installed — usually local councils — The Cloud and the internet service provider.

Mr Polk said that the programme will also be extended to other cities later in 2006. The first nine networks should be in place by March next year.

Canary Wharf, in London’s Docklands, recently launched a network and it is understood that the City of London is planning its own network.

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