Japanese mobile phone giant NTT DoCoMo is spending $9.9bn on a 16% stake in America's AT&T Wireless.

The move is part of the company's efforts to establish a leading position in the third generation (3G) mobile phone market.

DoCoMo is preparing to roll out the world's first 3G mobile phone services in Japan next May.

DoCoMo, with the huge take-up of its i-mode service in Japan, is already leading the world in making the mobile internet a commercial success - in stark contrast to the lacklustre take up of WAP services in Europe.

The firm, which has also been developing partnerships in Europe, plans to provide its US partner with the technology and know-how behind its platform for 3G phones, and its i-mode mobile internet service.

Lessons from Japan

AT&T Wireless International president Jordan Roderick said he hoped to recreate in the US the success of i-mode - which has 15 million users in Japan.

In Europe, internet services for mobile phones have been marketed largely as a means for users to keep abreast of news headlines or share prices.

But in Japan the i-mode service has focused largely on entertainment, proving popular with the teenage market.

Global interests

The US investment, plus a further $537m investment in Taiwan, follows the purchase of 20% of the UK's Hutchison 3G, 19% of Hutchison Telephone in Hong Kong, and 15% of Dutch telecoms company KPN Mobile in the past year.

"We are going to have a common infrastructure coverage all over the world," said Kiyoyuki Tsujimura, managing director of DoCoMo's global business.

In the US, AT&T Wireless has 15 million subscribers, representing a market share of 12%.