ASK Jerry Roest what will be playing in Europe’s clubs and bars this summer and he replies with unusual confidence for someone of 49.

It’s not that he spends his nights out on the town. He runs Shazam Entertainment, a service that identifies modern music through mobile phones.

If you are in a club at two in the morning and want to know what the DJ is playing, dial 2580, hold up your handset for 30 seconds and moments later you should have a text message identifying the record and the artist. All for 59p. You can then send a clip of the song to a friend or, depending on how you feel next morning, order the CD over the web.

With 750,000 users in Britain, Shazam is starting to become a good indicator of future hits. Before Panjabi-Mc, a British Asian artist, was on the radio or in the shops, for instance, he was being played as a dance track in clubs and was Shazam’s No1 request for weeks. He later went on to top the official charts. It is little surprise that the music industry closely watches Shazam’s weekly chart of pre-release tracks.

Shazam was dreamt up in 1998 by a Californian MBA, Chris Barton. “If audio technology can recognise voices, then why not music as well?” he wondered. A succession of experts said it would never work. But Barton persisted and finally found Avery Wang, a specialist from Stanford with four degrees in mathematics and electronic engineering. With £750,000 from some leading names in the music industry, Wang created a digital fingerprint for each track. As it was just a tag, Shazam could build a database of 2m tracks without infringing copyright.

Barton now had to convince mobile operators that the service could generate traffic and revenue. London was the best place to start, he decided, and by the summer of 2002 he had persuaded the four main carriers to use the service.

Three weeks after the launch, Radio1 DJ Jo Whiley gave listeners a chance to try the “black magic” that identified songs, playing an unreleased track from Janet Jackson. Shazam’s 30 lines were overwhelmed.

To turn a gizmo into an international consumer business, however, the investors wanted to appoint a professional manager to handle the tough negotiations with the music business and mobile operators. They selected Roest, an online veteran who had worked for the Financial Times, Compuserve and NTL. He started in the summer of 2002.

Roest moved Shazam from Regent Street to a former tax office in west London and made 17 people redundant. He also realised that the original idea of targeting 18 to 25-year-olds was misplaced. A much wider age group was interested, though not in a consistent way. “People use Shazam three or four times in a week, then not for six months,” he said.

New services, such as ringtones, are being added, and Shazam is working with record labels to promote new releases.

Last September, Sting became the first artist to promote an album through a new Shazam service, Mass Songmail. Fans rang to hear a clip of his single, Send Your Love, and to enter a competition. More promotions are planned with the Ministry of Sound and other labels. “We do everything first in the UK,” said Roest. “It is a test-bed and showcase for all our other partners.”

Agreements are now in place for Shazam’s technology to be used under a local brand in 10 different countries, with eight more to follow. AT&T Wireless in America is the latest to sign up. By the end of this year, Roest is hoping that Shazam will be available to 500m mobile users around the world.