Aiming to challenge the dominance of cell phones, Research In Motion Ltd. of Canada will launch a Japanese version of the BlackBerry 8707h through NTT DoCoMo Inc.'s sales network next Monday, targeting corporate users, the companies said Tuesday.

DoCoMo began selling English-language BlackBerry services last September to corporate users only, mainly non-Japanese working at multinational companies.

The market for BlackBerrys and multifunctional "smart" phones is expanding, with about 15 million end-users in 2006 worldwide. That figure is estimated to increase to 130 million by 2010, according to industry research firm Gartner Inc.

Joe Caci, Research In Motion's vice president in charge of Japan products, called the Japanese market "large" and "sophisticated."

The company and its partners see a chance to tap into that market by localizing the product, he said.

Analysts and longtime users are not so impressed.

Reiji Shibata, former president of the Japanese unit of Mercer Human Resource Consulting, who until last month used an English-language BlackBerry, said he initially thought the device was a "big help" in replying to a constant stream of incoming e-mail.

However, Shibata lost his BlackBerry and replaced it with a Softbank multifunction phone manufactured by Nokia. He said he gets similar functions with his cheaper handset.

"I think the BlackBerry market (for Japanese corporate users) won't expand as much as it did for foreign corporate users," he said.

Industry analysts also say Japanese have plenty of other ways to keep in touch with their company.

"There is no reason to exclusively buy BlackBerry. Japanese cell phone screens are getting bigger and many Japanese feel more comfortable with typing a message using one thumb rather than both thumbs," said Nahoko Mitsuyama, principal research analyst at Gartner Japan Ltd.