Apple Inc. plans to begin producing this year a new iPhone that could allow U.S. phone carriers other than AT&T Inc. to sell the iconic gadget, said people briefed by the company.

The new iPhone would work on a type of wireless network called CDMA, these people said. CDMA is used by Verizon Wireless, AT&T's main competitor, as well as Sprint Nextel Corp. and a handful of cellular operators in countries including South Korea and Japan. The vast majority of carriers world-wide, including AT&T, use another technology called...