Verizon Wireless is backing a free operating system that competes with programs from Microsoft Corp., Google Inc. and Qualcomm Inc. and expects it to become the "preferred" software on its network.

It's the first U.S. carrier to join the LiMo Foundation, which aims to unite handset makers, software companies and carriers on a software platform that will make it easier and cheaper to create a wide variety of phones.

The carrier's endorsement Wednesday is an important boost to the stature of LiMo, or Linux Mobile, and its prospects in the U.S. It already has the backing of large Asian and European carriers, as well as handset makers like Motorola Inc., Samsung Electronics and LG Electronics.

"There is now no doubt that LiMo-powered devices will comprise a significant percentage of many operators' portfolios," said Stuart Carlaw, cell-phone industry analyst at ABI Research.

Kyle Malady, vice president of network for Verizon, said he expects the company to sell both simple and "smart" phones using LiMo next year. That's a potential blow to Qualcomm, which supplies the software for most of Verizon's phones, excluding smart phones.

"We expect that Linux Mobile will rapidly become our preferred operating system," Malady said. "As the development community looks at how best to bring new applications to the marketplace, they should check out LiMo and Linux Mobile first."

But the company is not adopting LiMo to the exclusion of other operating systems, he added - it now sells phones with a variety of operating systems, and expects to continue doing so.

Verizon Wireless is also in the process of opening up its network on a wholesale basis to any device that meets basic technical requirements, but Malady made clear that the backing of LiMo is separate from that initiative, and the company plans to sell LiMo devices under its own brand.

While Verizon Wireless expects the adoption of LiMo to speed development, the difference between it and current cell phone software may not be apparent to users. The software package does not include a user interface, so the look and feel of LiMo phones may be borrowed from current phones.

LiMo's software is based on Linux, a freely distributed operating system that's mainly used in server computers and in niches like TV set-top boxes, where Microsoft's dominant Windows system doesn't reach.

The foundation released the first version of its software package in March, and Motorola, Samsung, LG and Panasonic have showed off phones using it. Motorola also has older phones that use its own flavor of Linux.

While more than 90 percent of PCs run Windows, the market for cell-phone software is much more fragmented. Microsoft has its own software for "smart" phones. Symbian Ltd., whose main backer is Nokia, sells the competing Series 60 software. Verizon Wireless uses a system from Qualcomm Inc. for most of its phones. Apple Inc. created its own software for the iPhone. Google Inc. is backing an Open Handset Alliance that is creating yet another system, called Android. The first phones running that software are expected later this year.

"The mobile industry really was very reluctant to follow the path of the PC industry and cede the heart of the device to any single company," said Morgan Gillis, executive director of the London-based LiMo foundation. "This is really why Microsoft has not gained any significant traction with Windows Mobile, and also why Nokia has not been successful with Series 60 as an industry platform proposition."

To try to unite the industry, four major handset makers, plus overseas carriers Vodafone Group PLC and NTT DoCoMo, set up the LiMo Foundation last year as an organization that is not governed by any one company, making software that will be free for everyone to use.

Malady said Verizon Wireless chose to put more weight behind LiMo than Android because LiMo unites diverse industry participants in an inclusive governance structure and has software available already.

Also joining the LiMo Foundation on Wednesday were SK Telecom Co., the largest carrier in South Korea, and the Mozilla Corp., which puts out the popular Firefox Web browser. Like Linux, Firefox is maintained on an "open source" basis, where everyone has free access to the software's blueprints.