Microsoft said it will unveil the newest version of its mobile-phone software next week at 3GSM World Congress, a pivotal industry gathering in Barcelona, Spain.

Windows Mobile 6, which will start shipping in April, adds a number of features to Windows Mobile 5.0, which Bill Gates unveiled almost two years ago.

In many ways, the older version helped make Microsoft a contender in the high-end mobile phone category.

But Mobile 6 may determine whether the company can gain an edge against more well-established rivals.

"This is a capstone release for us that has hallmark capabilities that will take the business to the next level," said Scott Horn, director of marketing for Microsoft's mobile and embedded-devices group.

The Windows Mobile operating system has gained a lot of ground in recent years.

Microsoft launched with one carrier in 2002; today it works with 48 device makers and 125 mobile-phone operators in 55 countries.

Its main competitors are Research in Motion's BlackBerry in the U.S., and Symbian, an operating system used widely around the world, mostly by Nokia.

Those companies enjoyed early leads, but Microsoft is catching up; it shipped 6 million devices in its last fiscal year, Horn said.

In first nine months of 2006, Gartner reported that smartphone shipments worldwide totaled about 52.7 million.

Prominent carriers using Windows Mobile include Cingular Wireless, T-Mobile USA and Orange in the United Kingdom.

As far as devices, Microsoft has had a few splashy launches, including the Motorola Q, Samsung BlackJack and T-Mobile Dash, developed by HTC.

Microsoft has made tweaks in the new Mobile 6 release and generally tried to make the software easier to use.

Here are some new features:

• E-mail: Users can receive e-mails with pictures, tables and formatting if a company has Exchange Server 2007, or from Web-based e-mail accounts.

• Microsoft Office: The new Office Mobile will let users view and edit documents.

• Windows Vista: Windows will use the Windows Mobile Device Center, which replaces ActiveSync in the old phones and allows music, pictures and movies to flow between the PC and device.

• Windows Live: Windows Mobile users can easily use and leave Live running in the background, including Mail, Messenger, Search and Spaces.

Phones with Windows Mobile 6 will come out in the next few months. Upgrades will be offered to current Windows Mobile users through their carrier.

Tricia Duryee: 206-464-3283 or tduryee@seattletimes.com