Microsoft unveils voice assistant Cortana to rival Apple's Siri

Joe Belfiore, vice president of the operating system group at Microsoft, holds a pair of mobile phones featuring the new Windows 8.1 operating system during the company's "build" conference in San Francisco, California April 2, 2014. REUTERS/Robert Galbraith

SAN FRANCISCO (Reuters) - Microsoft Corp on Wednesday formally announced it has developed a voice activated phone assistant feature called Cortana, a direct rival to Apple Inc's Siri. The feature has been rumored for some months and a test version was demonstrated by Joe Belfiore, a Windows Phone executive, at Microsoft's annual developer conference in San Francisco. The Cortana service, which can take verbal instructions to search the Web, set alarms, make calls and a host of other actions, is still in beta testing, said Belfiore, but will soon be a standard feature on Windows phones. Belfiore announced that the latest version of Microsoft's smartphone software, called Windows Phone 8.1, will be rolled out to consumers as a downloadable upgrade in the next few months, and new phones running the software will be in stores by late April or early May. (Reporting by Bill Rigby. Editing by Andre Grenon)