Microsoft is preparing to ship its Windows Phone 8.1 update with two significant changes: a notification center and a Siri-like personal assistant. Sources familiar with Microsoft’s plans have revealed to The Verge that the company is currently beta testing copies of Windows Phone 8.1 internally, with plans to fully detail its features at the Build Developer Conference in April, 2014. A highly requested notification-center feature will be added to the software, and we’re told it’s enabled by swiping down from the top of the screen in a similar way to iOS and Android.

New quick settings are exposed by a short swipe from the top, and a longer swipe will display a full notification history in current beta versions of Windows Phone 8.1. Both additions address some highly requested features in Windows Phone. Another key feature in the upcoming 8.1 update is the inclusion of "Cortana," a personal digital assistant. Microsoft has been testing Cortana for a number of months, and we understand it will replace the existing Bing search on Windows Phone to allow users to interact using voice or text input. We’re told it’s similar to Google Now and Apple’s Siri technology, with conversational interaction and the ability to learn location context and data from the phone. Like Google Now, it will automatically remind you when a meeting is approaching and how long you’ll need to reach an appointment.

Separate volume controls and VPN finally on the way

Microsoft is also building other new features into Windows Phone 8.1, and the company continues to address a number of missing parts along the way. Separate volume controls are finally being added to Windows Phone 8.1, allowing users to control ringtone volume independently of media playback. Microsoft is also adding Bing Smart Search results that are similar to Windows 8.1, and VPN support for enterprise users. In keeping with plans to update the video and music parts of Windows Phone more regularly, Microsoft is also separating out the built-in music hub in Windows Phone 8.1. Xbox Music and Xbox Video will ship as separate apps for 8.1, and we understand Microsoft is considering similar changes for other built-in apps for future Windows Phone updates. Microsoft is also planning to allow social apps like Twitter and Facebook to extend the People Hub even further in Windows Phone 8.1.

While Microsoft is busy preparing software features for Windows Phone 8.1, Nokia is readying two handsets for the OS update. One particular device, codenamed "Goldfinger," will include a "3D Touch" system that detects off-the-glass interactions. Nokia’s second handset, codenamed "Moneypenny," will take advantage of the new on-screen Windows Phone 8.1 buttons that are available to device makers with Microsoft’s latest update. Although Microsoft has recently started expanding its testing of Windows Phone 8.1 features internally, the update is not expected to be unveiled until Build 2014.