Google’s long list of powerful partners illustrates the substantial inroads that the company has made in the highly competitive industry as well the challenges still facing the giant search engine firm. For example, the two largest cellular carriers in the United States, AT&T and Verizon Wireless, which together account for 52 percent of the market, are not part of the alliance.

Still, alliance members, which contributed technology to the project, said they had high hopes for it.

“Just like the iPhone energized the industry, this is a different way to energize the industry,” said Sanjay Jha, chief operating officer of Qualcomm, which makes chips used in wireless phones. Mr. Jha said the Google technology would bring better Internet capabilities to moderately priced phones. He also said that innovation could accelerate, as developers would be able to enhance the software as they saw fit.

Users would have the ability to load up their phones with new features and third-party programs.

“Today the Internet experience on hand-held devices is not optimized,” said Peter Chou, chief executive of HTC, one of the largest makers of smartphones. “The whole idea is to optimize the Internet experience.” Mr. Chou, whose company makes several phones based on Microsoft’s software, which are largely aimed at business users, said the phones based on Google’s technology would probably be marketed primarily to consumers.

The alliance represents a bold move by Google and its partners that mirrors the company’s efforts in the desktop computing industry to give away software and services and gain revenue through targeted advertising. As such, the new software strategy is a potential competitive threat to Microsoft and other mobile software and hardware designers.

John O’Rourke, general manager of Microsoft’s Windows Mobile business, said he was skeptical about the ease with which Google will be able to become a major force in the smartphone market. He pointed out that it had taken Microsoft more than half a decade to get to the stage where the company now does business with 160 mobile operators in 55 countries around the world.

“They may be delivering one component that is free,” he said. “You have to ask the question, what additional costs come with commercializing that? I can tell you that there are a bunch of phones based on Linux today, and I don’t think anyone would tell you it’s free.”