One & Co. will retain its name and continue to serve other clients, HTC said. Past One & Co. customers include Nike, K2, Sony, Timex and Microsoft.

The two companies began working together in 2006 on the design of the HTC Touch Diamond, a touch-screen phone that has been compared to the iPhone and was released in the U.S. during the third quarter by Sprint.

HTC is not alone among mobile-phone makers in trying to emulate the iPhone, although none of the manufacturers has yet to match Apple's success. But relying more heavily on designers could be just what a manufacturer like HTC needs to better compete with the popular iPhone.

"A lot of people are trying to steal the thunder from Apple," said Satoshi Nakajima, who spent more than a decade at Microsoft, started software platform developer UIEvolution and most recently started up iPhone application developer Big Canvas. "But unfortunately they are focusing on touch screen or bigger screens, and those are just pieces. The completeness of the user experience is difficult to steal."

Nakajima, who spoke generally about the competitive mobile-phone market, made his comments before HTC announced its acquisition.