Verizon Wireless plans to open its network to devices other than the ones hand-picked by the company, a move that could expand the features available on mobile phones and give the second-largest U.S. wireless carrier a response to a phone software project led by Google Inc.

The decision, announced Tuesday, means that customers would be able to buy devices of their own choosing and run them on Verizon's network.

Traditionally, wireless providers like Verizon let customers pick only carrier-approved devices, with carrier-approved software features.

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The model has some benefits for consumers, because many of the available phones are subsidized by the wireless provider. That means devices that would otherwise cost hundreds of dollars are available for under $100 or even for free.

But because this "walled garden" approach dictates which services customers can use — so as to maximize profits for the carriers — the traditional model has not created a broad, open environment commonly thought to best encourage outside software developers.

It is as if some Web sites ran only on certain brands of PCs.

Verizon's new plan, which is expected to be running by the second half of 2008, will hardly be taking a sledgehammer to the walled garden.

The traditional model, in which Verizon selects phones to sell, will still exist. And the company will let customers operate other phones on its network only if the devices have passed tests, which their manufacturers will pay for, in a Verizon lab.

Even so, Verizon's announcement indicated it was willing to try out the idea that customers want more flexibility in what they can do with their phones — even though it could force the carrier to make do with being a basic provider of wireless access rather than a value-added content provider as well.

There was no mention of whether Verizon would somehow admit phones using the GSM standard, such as models that run on AT&T Wireless's and T-Mobile's networks, as well as the CDMA phones Verizon and Sprint customers use.

GSM phones are commonly sold "unlocked" in Europe, where the customer can buy a calling plan separately. But all CDMA phones in the U.S. are set to use a specific carrier.

Tuesday's news gave Verizon Wireless — a joint venture of New York-based Verizon Communications Inc. and Britain's Vodafone Group PLC — the second landscape-shifting announcement in the wireless industry this month.

In hopes of making Web surfing and other advertising-supported features more prevalent on cell phones, Google said Nov. 5 it was developing a free software package for wireless devices to operate on.

Key phone makers, including Motorola Inc., Samsung Electronics Co., and LG Electronics Inc. have agreed to use it in some devices. And some wireless carriers, including Sprint Nextel Corp. and Deutsche Telekom AG's T-Mobile, have said they would support devices with the software on their networks.

Verizon Wireless is not in the mix, at least for now. (Nor is the largest U.S. wireless provider, AT&T Inc., the sole domestic carrier of Apple Inc.'s innovative iPhone.)

However, Verizon Wireless spokeswoman Nancy Stark said a phone with the Google software could make it onto Verizon's network through the new plan to let customers buy their own devices separately.

The flexible approach was praised by the Federal Communications Commission chairman, Kevin Martin, who has pushed carriers to allow open-access freedoms as a condition of an upcoming auction of the airwaves.

Telecommunications analyst Dave Burstein, editor of the DSL Prime newsletter, predicted that the "wonderful" new approach would lead to phones with such innovative specialties as extremely cheap international calling or exceptionally long battery life.

Verizon's plan also has support from Microsoft Corp., which would love to get its Windows Mobile software into more consumers' hands.

"This is a big step in a journey that the entire industry is making," said Scott Horn, general manager of Microsoft's mobile communications business.

However, it's unclear how much effect Verizon Wireless' venture will have. One reason is the lab testing for third-party devices.

Gartner Inc. analyst Ken Dulaney said that process could be so slow as to hinder the envisioned onslaught of creative new devices. Verizon Wireless executives pledged that it would be a simple process in the range of weeks, not months.

Also, until some killer application emerges, it's unclear how many consumers would prefer to buy their own, unsubsidized device and then sign up separately for time on Verizon Wireless' network.

"U.S. consumers are used to the idea that a phone costs $50-$100. This is going to be jarring to the mass audience," said Charles Golvin, an analyst with Forrester Research.

The advantage could be that such a customer might be able to bring the device to other carriers that share Verizon's CDMA network standard, assuming they follow suit with such an open-access plan.

That freedom, like other consumer liberties, have been lacking in the wireless phone business.

"I hope this catches fire, and I hope this goes across the world," Dulaney said, "because it is the way to make wireless data more successful."