Confirming its long-rumored foray into the mobile market, Google said Monday it is developing a free cell phone software package so the Internet search leader can more easily peddle ads and services to people who aren't in front of a PC.

Google's system will also be based on computer code that can be openly distributed among programmers. That, Google hopes, will encourage developers to create new applications and other software improvements that could spawn new uses for smart phones. A development tool kit for working on the new platform will be released next week.

The list of wireless carriers that have agreed to provide service for the Google-powered phone in the United States include Sprint Nextel Corp. and Deutsche Telekom's T-Mobile in the United States. China Mobile, Telefonica in Spain and Telecom Italia are among the carriers that have signed on to provide service outside the United States.

They are among a Google-led group of 34 companies that have formed the Open Handset Alliance. Other key players include major chip makers like Intel Corp., Qualcomm Inc., Texas Instruments Inc., Broadcom Corp. and Nvidia Corp.