At the 2011 Mobile World Congress, Steve Ballmer announced a major update to Windows Phone 7 due toward the end of the year, Windows Phone 7.5, codenamed Mango. The new OS would address many of the platform's shortcomings, including a mobile version of Internet Explorer 9 that supports the same web standards and graphical capability as the desktop version, multi-tasking of third-party apps, Twitter integration for the People Hub, and Windows Live SkyDrive access. Although the OS internally identifies itself as version 7.1, it is marketed as version 7.5 in all published materials intended for end-users.
Microsoft started rolling out Windows Phone 7.5 to both the United States and International markets on September 27, 2011. The first phones that came pre-loaded with Windows Phone 7.5 were released in the last quarter of 2011.
A minor update released in 2012 known as "Tango", along with other bug fixes, would also lower the hardware requirements to allow for devices with 800 MHz CPUs and 256 MB of RAM to run Windows Phone. Certain resource-intensive features are also disabled on these phones, and the Windows Phone Store will also prevent the installation of apps that are considered to be too intensive for use on weaker hardware. The lower requirements were adopted in order to allow the development of lower-cost devices, particularly to target emerging markets such as China.
Touch focus and capture—Tap any spot on the screen to focus there and take the shot. (This varies according to hardware—some phones will have tap-to-capture but will still automatically center focus.)
Review pictures above the lock—Snap a photo when your phone is locked, then take a peek at it above the lock. You’ll only be able to get to photos you just took—better for security.
Changes for portrait orientation—Now, when you take a picture in portrait orientation, you’ll see it in portrait orientation when you review it.
Third-party application multi-tasking and fast application switching.
Support for background tasks and services/agents.
Expanded live tiles that can be updated without network connection and can have two sides which flip periodically.
App Connect: third-party applications can integrate with Bing search, have multiple live tiles, and can have push notifications that link deep ("Deep Toast") into various parts of the application directly.
Optional 32 bit color support for Silverlight applications with hardware dithering.
Silverlight 4 support.
Silverlight + XNA support in the same application screen.
Raw camera feed access for third-party applications.
New sensor API combines compass, gyroscope, and accelerometer.
Improved Listbox control with better scrolling performance.
Improved WebBrowser control with IE9 rendering engine and system-wide cookies access.
Hardware-accelerated video decoding in the MediaPlayer control.
TCP/IP and UDP sockets support.
Embedded database with LINQ (based on SQL Server Compact 4.0 engine, but without direct SQL execution).
Background file transfer agent.
Generational garbage collector.
NEON/SIMD support for XNA applications.
Fixed email issue in Microsoft Exchange Server 2003
Also confirmed are 23 additional markets including; Bahrain, Bulgaria, China, Costa Rica, Croatia, Estonia, Iceland, Iraq, Israel, Kazakhstan, Latvia, Lithuania, Qatar, Romania, Saudi Arabia, Slovakia, Slovenia, Thailand, Turkey, UAE, Ukraine, Venezuela and Vietnam. This update will also include a Skype application.
The Nokia Lumia 610 and ZTE Orbit, introduced at Mobile World Congress in 2012, are the first phones to run the Tango update.
Fixes an issue with app purchases in some regions.
Previously released Windows Phone hardware is incapable of being upgraded to Windows Phone 8, due to changes in the kernel requirements and hardware specifications. However, Microsoft announced at the Windows Phone 8 announcement event that Windows Phone 7.x devices would receive a free upgrade to Windows Phone 7.8. Microsoft announced Windows Phone 7.8 alongside Windows Phone 8 and began pushing the update to devices in January 2013. It added some features from the Windows NT based Windows Phone 8, backported to Windows Phone 7. These features included the updated start screen that allowed users to resize live tiles, additional theme colors, and an update to the lock screen that would optionally display the daily Bing homepage picture automatically. Windows Phone 7.8 does not support USSD.
General Distribution Release 1, a minor update known as Portico was rolled out on December 2012 that brought some improvements and bugfixes, including enhancements in Messaging, more efficient Bluetooth connectivity, and an "always-on" setting for WiFi connections, among other additional platform updates
Microsoft rolled out a package of minor updates called General Distribution Release 2, beginning in July 2013 and spanning the following months, depending on the manufacturer and carrier. Along with this update Nokia released its own update which updated the firmware of the user, namely Lumia Amber, which was available for only Lumia phones. The update brought many camera improvements and fixed some bugs in the cameras of existing Lumia phones.
On October 14, 2013, Microsoft released the third General Distribution Release update for Windows Phone 8, which would roll out to phones over the following months. Windows Phone Developers were among the first to receive the update under a new Developer Preview Program.
General Distribution Release 1 (GDR1; also referred to as Update 1) adds new language and region support for Cortana, the option to organize apps into folders on the Start Screen, SMS forwarding of multiple messages, improvements to Xbox Music, a live tile for the Windows Phone Store and an option for sandboxing applications. In addition, Update 1/GDR1 also includes new VPN and Bluetooth features for enterprise users, as well as support for interactive cases such as HTC's "Dot View" case, larger "phablet" screen resolutions such as 1280x800, 540x960 qHD and 1280x768 and the Qualcomm QuickCharge 2.0 standard.
Microsoft has made several changes to Internet Explorer Mobile that brings the browser experience closer in line with the experiences on Safari (iOS) and Chrome (Android). To accomplish this, Microsoft moved away from open standards and adopted non-standard features used in Safari and Chrome, implemented browser detection, improved page rendering by detecting legacy WebKit features, brought support for HTML5, and fixed interoperability issues with bad HTML code.
An example for the comparison of the changes made to the user-agent string in Update 1/GDR1 in order to overcome erroneous methods of browser detection and correctly deliver mobile content to Internet Explorer Mobile.
IE11 on Windows Phone 8.1: Mozilla/5.0 (Windows Phone 8.1; ARM; Trident/7.0; Touch; rv:11; IEMobile/11.0; NOKIA; Lumia 928) like Gecko
IE11 on Windows Phone 8.1 with Update 1/GDR1: Mozilla/5.0 (Mobile; Windows Phone 8.1; Android 4.0; ARM; Trident/7.0; Touch; rv:11.0; IEMobile/11.0; NOKIA; Lumia 720) like iPhone OS 7_0_3 Mac OS X AppleWebKit/537 (KHTML, like Gecko) Mobile Safari/537
Information regarding GDR2 (also referred to as Update 2) was released in February 2015 it was revealed that Microsoft was working on a 2nd update for Windows Phone 8.1 that would provide increased security for OEM's, add extra languages and additional technology support and is also reported to bring an anti-theft mode.
Action Center showing either standard or silent toast notifications, accessed by swiping from top to the bottom
Quick settings access in action center with four (or five on large screens like 6 inch Nokia Lumia 1520) configurable shortcuts to: Airplane mode, bluetooth, brightness, camera, internet sharing, location, project screen, Quiet Hours, rotation lock, VPN, Wi-Fi [items in this list cannot be changed]
Start screen backgrounds
Support for start screen live tile rows of up to 6 small or 3 medium live tiles
'Cortana' smart personal assistant, based on the Bing service [available only on limited number of markets]
Swipe down to close apps in multitasking view
Recently installed apps are annotated with 'NEW' in the app list
Support for virtual on-screen buttons called 'Navigation bar' with custom background color selection
Gesture keyboard, that is, swipe across letters on keyboard to type (Shape Writing) [not available on all languages / keyboards types]
General user experience changes
Bing smart search (similar search system as Windows 8.1)
Back button doesn't close application
Contact speed dialling
Ability to show only Contacts with phone number
Contacts with 'Inner Circle'; up to 40 Contacts (requires Cortana support)
Double-Tap to unlock your phone (Feature from Lumia devices on Amber Update and newer)
Favourite photos by tapping a heart icon
General keyboard enhancements including show emoji when typing and recognize names of Contacts
In-call speech commands
Notification if charger isn't of adequate power
Quiet Hours - Disable notifications during pre-selected time-frame or when 'Busy' in calendar (requires Cortana)
Screenshot button combination is now Power + Volume Up
Search button will be the new way to open Speech (aka ‘Cortana’)
Separate volume controls for ringtones/notifications and music/media
Set default Voice Navigation app for the OS
Voice Narrator for Accessibility
Wi-Fi Sense: sharing secured Wi-Fi Networks with contacts if they have Wi-Fi Sense
Wi-Fi can auto re-enable after a set duration of time
Status bar with Signal strength, Wi-Fi, Battery etc. is always visible (doesn't auto-hide)
Phone history group repeat calls from a user annotated with number of calls
540 x 960 qHD resolution support for diagonal screen sizes up to 6"
1280 x 768 WXGA resolution support for diagonal screen sizes of 6.01" to 7
Possibility to install Wi-Fi Feature Pack which removes all cellular-related functionality from the operating system
August 19, 2014
September 24, 2014
Fixes error 80188308 some users were experiencing during update ( works in HTC 8X India model- in preview for developers )
HTC Windows Phones 8X, 8S, and 8XT will now be able to get the Windows Phone 8.1 Update
Fixes an Access Violation in "minuser" component which caused WinRT apps and WebViews to crash if scrolled by the user while (or 2–15 seconds after) loading, which was a regression introduced in the 8.1 Update 1 release (8.10.14147.180).
October 24, 2014
Tests Microsoft's ability to distribute a "Critical Update". Note that this update does not actually contain critical fixes - it's just a test.
13 November 2014
"Critical Update" for unstated reasons
Allows for real-time Live Tile for the Battery Saver App (also allows you to add Battery Saver to the Quick Settings found in the Action and Notification Center)
Adds preferred install time for automatic updates
Made NTP time sync support enabled by default for CV devices (instead of rely on OEM to enable it)
December 5, 2014
New country support for Cortana; Spain, France, Germany and Italy (alpha). (However, due to a widespread bug in the deployment, Cortana is not available for many users)
Cellular Data Toggle for Quick Settings access in Action Center.
Support for offline maps storage on MicroSD card
Hardware keyboard support
Ability to use the SD card storage space temporarily for OS updates (must be enabled in the ROM)
December 24, 2014
Fixes screen issues on the Microsoft Lumia 535
February 24, 2015
Fixes screen issues on the Microsoft Lumia 535 (not be solved with the previous update)
Windows 10 Mobile was announced on January 21, 2015, as a mobile operating system for smartphones and tablets with screens smaller than 8 inches, with the first build released on February 12, 2015. It is the successor to Windows Phone 8.1 and will replace the Windows Phone brand. Windows Phone 8.1 devices will be eligible for upgrade to Windows 10, pursuant of manufacturer and carrier support. Some features may vary depending on hardware compatibility.