Watch the official demo of Windows Phone 8.1 from Microsoft. It shows lots of new features that will be part of Windows Phone 8.1 update including new lockscreen experiences, calling experiences, and more. Windows Phone 8.1 will start rolling out to existing Windows Phone 8 users and will come pre-installed on new phones, including the Lumia 630 and 635 and Lumia 930 announced by Nokia today, in the coming months. If you want to try out Windows Phone 8.1 and you are a registered developer, you can update your phone as part of the Developer Preview Program in the first part of April. Watch the promo of Nokia Lumia 930, Lumia 630 and Lumia 635 after the break.