Top-tier players such as Nokia Corp., Motorola Inc. and Samsung Electronics Co. control 80% of the market for cellphones but have struggled in the U.S. to sell smart phones -- phones that allow users to surf the Internet, send email and download music, among other advanced functions.

Often caught up satisfying carrier demands, handset makers have been slow to bring out products in this segment, opening the door for the likes of Research in Motion Ltd. and Apple Inc.

This could prove a crucial error for the traditional players, as they cede the fastest-growing and most profitable slice of the market. "They're really missing out on a critical high-end segment," said Hugues De La Vergne, an analyst at Gartner Inc.