Windows Phone 8.1 adds voice assistant Cortana and a new lockscreen

SAN FRANCISCO — During the company’s keynote address at its Build developer conference Wednesday, Microsoft introduced Windows Phone 8.1, the newest version of its phone operating system. The long-awaited release brings Cortana, a voice assistant to rival Siri, a new lockscreen and Action Center notification drawer.

Cortana replaces the earlier voice command feature in Windows Phone. Like Siri, Cortana is a she, and you can talk to her to search the Web, ask for directions, and more.

Action Center pulls down from the top of your phone’s screen and gives you settings toggles, plus notifications from your apps. You can customize which apps show up there.

The new lock screen shows the time and date, notifications, and upcoming calendar events. You can customize the background, like you could do in previous versions of the mobile OS. There are special animations that change how items move on the lock screen when you swipe to unlock your phone.

The Start screen, or home screen on your phone, now supports an extra row of tiles. You can also set a wallpaper, which shows up in you tiles.

This is the fourth generation of the Windows Phone OS, and it replaces the earlier Windows Phone 8. That version was updated in October 2013 with Windows Phone 8 Update 3, which added a new row of live tiles to the home screen on larger phones, task-switching, and a driving mode.

This is a developing story. Follow CNET’s live blog of the Microsoft Build keynote.