"We estimate 46 of the 50 most-used smartphone apps will be on Windows Phone 8," said Belfiore.

Users will have a selection of around 120,000 apps available for the phone, he said. "That's huge progress for us."

A new lock screen that shows app content, such as sports scores, news or favorite photos, rather than a static image, was another of the features shown Monday.

Microsoft also announced Data Sense, which helps users manage their smartphone data usage. Belfiore said the app had helped testers get 45 percent more Web browsing before hitting their data limit with the feature switched on.

To work, the feature needs carrier support. Verizon will be the first carrier in the U.S. to support it. Other carrier partners were not announced.