LAS VEGAS -- The next version of Windows Phone, expected to launch in the spring, will be backwards compatible to Windows Phone 8.0, contrary to some earlier reports from industry sources, a Microsoft official told Computerworld today.

That means that smartphones running Windows Phone 8.0 will be able to run the updated version, assuming that the user's wireless carrier has distributed the update to its customers.

"We will not have the same experience as we had when Windows Phone 7 was upgraded to Windows Phone 8," Greg Sullivan, Windows Phone director of public relations at Microsoft, said in an interview Wednesday at the International CES show here.

Users of Windows Phone 7 devices were upset that they could not upgrade their devices to Windows Phone 8, or WP8, when it was unveiled more than a year ago. Sullivan said that unlike Windows 7, WP8 is a "powerful OS" that can support upgrades. "We won't run out of head space on Windows Phone 8 any time soon," he said.

Microsoft has a policy of supporting updates for 36 months on a device, Sullivan said.

In late October, officials at three software vendors that work with Windows Phone products told Computerworld they were worried that WP8-based smartphones may not be upgradeable to the next version, believed to be version 8.1. They based their concerns partly on price cuts for Windows Phone 8 smartphones made by Nokia, Samsung and others, and slower than expected sales of such devices.

At the time, Microsoft wouldn't comment on its upgrade plans, though Nokia indicated that its Lumia 1020 and Lumia 520 smartphones would indeed be upgradeable.

Microsoft hasn't indicated when it will release the Windows Phone update, but many analysts believe it will be released in the spring time frame.

Microsoft is in the final stages of acquiring the device business of Nokia and seems prepared to continue using the Lumia name on some smartphones. "We will have the license for the Lumia name," Sullivan said.

Microsoft expects to continue Nokia's focus on using smartphone cameras with high-quality imaging technology such as the Lumia 1020 with a 41 megapixel camera, he added.

Following Intel's unveiling here of a dual Windows 8.1 and Android processor for tablets and computers, Sullivan said it's unlikely that Microsoft will support a dual OS. "A dual OS creates a lot of complexity for users," he said. It's not clear whether he was referring to just Windows Phone devices or also to tablets.

Following reports that Microsoft wants to reduce the number of operating systems it offers, Sullivan said "it's important to support both" Windows RT 8.1 for ARM-based devices and Windows 8.1 for Intel-based devices. The debate at Microsoft is whether it will continue "Windows Phone or Windows RT -- that's the question," Sullivan said.

ARM-based chips are used in nearly every smartphone in the world, including Windows Phone smartphones.

Windows RT for tablets has been widely criticized for not supporting traditional Windows-based apps, which limits its use for workers who have older applications running Windows.

But ARM chip makers such as Nvidia and Qualcomm have staunchly defended Windows RT for tablets, partly because the tablets running Windows RT can serve a new, younger audience that doesn't need access to older Windows apps, but still can take advantage of lower cost Windows RT tablets that are known for power efficiency.

Matt Hamblen covers mobile and wireless, smartphones and other handhelds, and wireless networking for Computerworld. Follow Matt on Twitter at @matthamblen, or subscribe to Matt's RSS feed . His email address is mhamblen@computerworld.com.

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