Shares in BT shot up 6.3 per cent to 945 pence ($1.53) as investors applauded a deal which promises a step advance in the company's capability in the fast-growing mobile market.

"It is good for BT's share price because the company has got together with one of the biggest beasts in the global jungle," said Nigel Hawkins of stockbroker Williams de Broe.

Terms of the so-called Advance alliance were not disclosed. The two companies are currently awaiting regulatory approval for their $10 billion global venture announced in 1998 designed to serve multinationals, carriers and Internet service providers.

The Advance pact plans to offer a new mobile Global Account Services package, which will give multinational customers global contracts and consolidated management information, the companies said in a joint statement.

The two companiesalso said they plan to grow revenues from roaming - a period when charges are applied if callers are outside their mobile network - by directing as much traffic as possible onto the two companies' own global networks and other initiatives.

AT&T and BT also said they would take a common position on the latest technologies, merging the use of the Internet and mobile services as well as pooling resources to gain economies of scale in purchasing and investment decisions.

"By pairing two of the leading telecommunications companies in the world, AT&T and BT, we think we can make some things happen that will eventually give customers those `anytime, anywhere' capabilities from their mobile phones," John Zeglis, AT&T's president, said in the statement.