The Treo 700w, available on the Verizon Wireless cellular service starting Thursday, also integrates access to Verizon's high-speed EV-DO data network.

While the original Treos - based on the Palm operating system - helped define the smartphone category, Sunnyvale, Calif.-based Palm hopes the new Windows-based model will expand its reach into the lucrative market of corporate users.

"IT managers in big corporations were saying they've standardized their platforms on Microsoft, and no matter what we did on the Palm OS, they just weren't going to use them," said Ken Wirt, Palm's senior vice president of worldwide marketing. "By doing one on Windows, we're addressing a bigger market."

Features such as accessing e-mail or phone contacts, for instance, becomes a smoother process because the Treo 700w now could work directly with businesses' servers that use Microsoft's Outlook mail program.

That also poses an increasing challenge to Research in Motion Ltd., the maker of the BlackBerry wireless e-mail device and gadgets that add phone functionality to wireless messaging.

Smartphones, which combine voice, data and wireless messaging capabilities, have been gaining in popularity and are seen as the wave of the future as they become more powerful and better equipped to handle functions previously reserved for laptops.

Microsoft's Windows platform for mobile devices, which analysts say does a better job than the Palm operating system when it comes to handling multimedia and intensive data applications, has steadily seized market share away from the once-dominant PalmOS provider PalmSource Inc.

In 2000, Microsoft had only about 11 percent of the handheld market. Now the Redmond, Wash.-based company has overtaken PalmSource, according to Gartner Inc. market research firm.

In the second quarter of 2005, about 560,000 smartphones equipped with Windows were shipped worldwide. Phones featuring PalmOS numbered 480,000.

Palm was careful to not make the Treo 700w simply a clone of other Microsoft-based handhelds, however.

Though Palm's groundbreaking deal to use Windows was announced in September, the two companies had been collaborating for more than two years, in part to negotiate how much leeway Palm would have to incorporate its own features on top of the Microsoft platform.

"We said we didn't want it unless we can make modifications," Wirt said.

For one, Palm made Microsoft's rival Google the default engine for Web searches on the Treo 700w.

Some of the distinguishing features are entirely new to the Treo line, while some are enhancements of features already found on the regular Treo, a device touted for its one-handed ease-of-use.

Those features include the ability to "dial by name" with just a few button clicks; one-touch dialing with personalized photo speed-dial icons; accessing voicemail with quick VCR-like icons to fast forward or delete; and the ability to store and quickly send preprogrammed short text messages, such as "Can't talk right now," when you're ignoring a phone call.

Business customers have sought a Windows-based Treo for years but Palm rightfully had to reach a decision of how they could add value on their own, said Creative Strategies analyst Tim Bajarin. "Once they got the OK to innovate, that's when they thought they could create a product that was compelling."

The new Treo "will be good for Palm's entire business," Bajarin predicted.

The Treo 700w costs $399.99 after a $100 instant rebate with a two-year service agreement.