The smartphones going into the world’s next two billion pairs of hands may not belong to either Google or Apple, but to Mozilla.

The Mozilla Foundation, which oversees open source software projects like the Firefox Web browser, expects to release a mobile operating system for smartphones early next year. Its target market is Latin America, then the rest of the developing world, where smartphones from Apple and Google are still too expensive for most people.

The Firefox models will be anywhere to one-third to one-sixth the cost of the competition, according to Mozilla and its partners.

“This is the connection of the world to each other” though mobile devices connected to the Internet, said Gary Kovacs, chief executive of the Mozilla Foundation. “This is about a standard, compliant easily accessible Web” for mobile devices, he said. The phones would be “in the middle of the high end of the feature set, and the low end of the price,” he said.

Mozilla’s main partner is Spain’s Telefonica, which already has about 215 million mobile subscribers in Latin America, and operates 6,500 stores worldwide.

Telefonica also has co-investments with China Unicom, a major Chinese carrier, and is an investor in Telecom Italia. Other carriers, including the German giant Deutsche Telekom, are also participating in the technical work. Qualcomm, a major maker of mobile phone chips, is also part of the Mozilla project.

“We are looking at a $100 to $115 price point” for the phone, said Carlos Domingo, director of product development and innovation at Telefónica Digital. He said the phone would have features associated with high-end phones using Apple’s iPhone or Google’s Android operating systems, he said, like a sharp camera, a big touch screen and an accelerometer. And, of course, a Firefox browser:

The Firefox phone will largely be sold in prepaid phone markets, where lower-income people typically buy their air minutes ahead of time. An Apple iPhone without a two year contract costs about $650. High-end Android smartphones cost $350 to $450 without a contract.

The carriers may welcome a competitor to Google and Apple, and thus participate in the Mozilla initiative as a way of ensuring that they are not always at the mercy of the two giants in terms of future technology. Qualcomm gets an outlet to sell more chips.

Mozilla hopes its phone will increase the use of the Web on mobile devices, instead of mobile apps created to work only with Apple or Google products. It still plans to release a mobile “store” where people can buy mobile software, but does not plan to police it, like Apple does, or block developers not working with Google, as the search company does with its store.

The Firefox smartphones will work according to technical standards that will make it easy for content developed for the Web to move to phones, Mr. Kovacs said, perhaps eventually eliminating the need for specially built mobile applications. Like its other products, the software for the Firefox phones will be free and open to inspection by anyone, he said.

There are already cheaper phones on the market, like the $70 model by China’s Huawei that is popular in Africa, where an economy tied to Amazon’s cloud computing is emerging. Those phones have tiny screens, Mr. Domingo said, and use older versions of Android.

The first manufacturers of the phones will be ZTE and the TCL Corporation, both Chinese manufacturers.