Installing Windows 10 Mobile

The simplest way to evaluate or deploy Windows 10 Mobile is on new hardware that ships with Windows 10 preinstalled by the device manufacturer. To evaluate Windows 10 Mobile on older hardware, be sure the device meets Microsoft’s requirements.

The device must have at least 8 GB of storage, must be running Windows Phone 8.1, and must be on the list of supported devices here: http://windows.microsoft.com/en-us/windows/preview-supported-phones. (To check which operating system version is installed on a Windows phone, go to Settings, About, More Info.)

If the device passes that check, you can install Windows 10 Mobile manually. If your mobile carrier offers Windows 10 Mobile as an over-the-air update, use that option. If not, you’ll need to bypass the carrier by joining the Windows Insider program. Start by enrolling at https://insider.windows.com using the same Microsoft account you plan to use with the phone. (If you previously enrolled in the desktop preview program with that account, you can skip this step.)

Then, on the supported mobile device, install the Windows Insider app from the Store and sign in using your Microsoft account. Choose the Get Preview Builds option.

As with the preview program for desktop releases, you can specify whether you want the device to be on the Fast or Slow ring. You must choose one of the two options when enrolling for the first time.

To see which ring your device is currently enrolled in, or to leave the Insider program, tap the ellipsis (three dots) at the bottom of the Windows Insider app and then tap About from the menu of options. To switch from Insider Fast to Insider Slow, or vice versa, run the enrollment process again.

Restoring the original operating system to a Windows 10 Mobile device (including the option
to restore Windows Phone 8.1 if you’re leaving the Insider program) requires a separate utility, the
Windows Device Recovery Tool. Information about the tool, including a download link, is available at
http://windows.microsoft.com/en-us/windows-10/windows-device-recovery-tool-faq. This requires a USB connection to the phone; the utility identifies the phone, downloads the current operating-system image for that device, and then replaces the preview build with the downloaded version.

Source of Information : Microsoft Introducing Windows 10 For IT Professionals