About 1,000 mobile phone users - including some from the BBC - will be involved in the trial, in the UK and Norway.

They will be able to access e-mails, calendar information and other data, including content from Web pages, specially tailored for small phone screens.

BT and Microsoft say that at the end of the three-month test, they expect to widely market the service in early 2000.

The trial follows an internal test of the service, and will help the companies to assess the market and gather feedback on how customers will use the wireless Internet service.

People involved in the trial will be from four customer companies - the BBC, Credit Suisse First Boston, KPMG and Nortel Networks, as well as business partner Telenor Mobil.

Future technology

Sohail Qadri, BT's director of mobility, said: "BT and Microsoft will enable their corporate customers to use vital computing and Internet-based business applications whilst on the move.

"For the first time, it will be possible for these companies to use mobile handsets to send and receive e-mails and operate an electronic diary working directly into a corporate server in real-time.

"The Internet and wireless markets represent the growth engines of high technology.

"There is a demand for this type of service from both multi-national and medium-sized enterprises."

BT is likely to charge either on the basis of minutes used or amount of data transmitted and pay Microsoft a fee for the service.