The move will initially target Japanese tourists before expanding to a community of some 350,000 Japanese living in the US, then other Asian residents.

"The US is a very important country to Japan," Atsuhiko Ohkita, Ericsson's senior market analyst in Japan, says. "Japanese move to the US in great numbers and we do lots of business there. But Japanese users complain about not being able to use their elegant phones in the US."

The US market has traditionally favored smart devices, such as the BlackBerry, which target business users as a path for potential growth. But sales in Japan have been consumer driven: people use their phones for e-mail, music downloads, games and mobile-wallet services, where financial transactions are paid via mobile phones.

Users in the US enjoy voice communications, almost five times the rate of usage for Japanese subscribers. Users in Japan enjoy data; e-mail, web access, and music downloads. Data traffic is almost double that for voice traffic. Some 20 million Japanese citizens already have mobile-wallet phones, and about 5 million use the service daily.

"In Japan, it is quite possible that ATMs (automatic teller machines) will completely disappear," Ohkita says. "The mobile phone is more than a communication tool."

New mobile services are regularly tested in Japan months, if not years, before they become available and popular in other markets such as the US.

In many ways that's no surprise: about 100 million of Japan's 127 million people have mobiles - one of the world's highest mobile-penetration rates.

In the US, Japanese tourists and immigrants will be the first targets of KDDI's launch. Other Asian communities will be identified and targeted later. Handsets capable of handling Japanese characters are expected to go on sale as early as June.

KDDI, avoiding any need to build expensive networks, will launch a mobile virtual network operator (MVNO) using Sprint Nextel to provide its services. Its decision to set up an MVNO in 49 of the 50 states (Alaska is the only state where it will not operate) is expected to increase the company's chances of success.