The Windows 8.1 update is here and Nokia Lumia 1520 gets the first taste of the new features and improvements of the operating system that include Cortana, Microsoft's digital assistant.

"The Windows Phone 8.1 update also takes full advantage of the Lumia 1520's quad-core processor, large, bright 6-inch HD 1080p display, and Nokia Rich Recording suite – four digital microphones and 140 dB recording range provide unparalleled stereo sound for video captured by the Lumia 1520," the AT&T announcement notes reads.

Windows answer to iOS's Siri, Cortana boasts a wide repertoire and can ensure that you do not get calls or texts when you do not want to be disturbed during your "quiet hours."

As a personal digital assistant she can do the following on the owner's behalf: make calls, send text messages, set alarms, take notes, browse through news and updates, view calendar entries, give alternate route to escape traffic jams, check weather and more.

Users can also now use their favorite photo as the Tile background on the Start Screen which fits together like puzzle pieces.

Windows Phone 8.1 update introduces "quiet hours," a feature that that when turned on will automatically redirect calls to voicemail and all notifications will be silent.

Another slew of features and functionalities include access to the Xbox Video app to get TV and films on the go, "shape writing" that offers predictive keyboard typing, Wi-Fi sense that helps save mobile data by connecting the phone to crowdsourced open Wi-Fi networks, bundled Skype, Internet Explorer 11, and improved notification system and spruced-up calendar.

Aside from the Windows Phone 8.1, Nokia Lumia models will also get the Cyan firmware update that will enhance apps like Storyteller, Creative Studio and Nokia Camera.

The Nokia Lumia 1520 that was released last November 2013 sports a 20MP rear-facing camera, 1080 x 1920 pixels display, quad-core 2.2 GHz Krait 400 processor and runs Qualcomm Snapdragon 800 chipset.