Users will also be able to sync Cortana on their handset with the personal assistant on their Windows PC. When running on a Windows Phone, the service offers even more, but how it performs on the iPhone or a Nexus device will be limited by the fact that it won't have the same levels of access to a handset.

Just how much won't be clear until it launches on Android at the end of June and for Apple devices some time later.

Microsoft is expanding Cortana to serve as a search engine and personal assistant, capable of answering questions and responding to commands such as "Play music" on desktop and laptop computers, as well as mobile devices.

The Windows 10 will also come with a new Web browser that will be closely integrated with Cortana, the Microsoft's voice-activated answer to Siri.