Microsoft Lumia 535, 640, 640 XL, 735, 830, and 1520 smart devices are eligible for a free upgrade to Microsoft Windows 10 mobile. These smart devices must currently have Windows Phone 8.1 Denim installed. Also, certain carrier’s might not have this upgrade available.
Microsoft Windows 10 mobile comes with Cortana, Microsoft Edge web browser, Maps, Calendar and Photos applications. Once installed automatic updates will be released in future. You want to download and install Windows 10 upgrade adviser from the Windows store.
This free application, will help you verify whether or not your Microsoft Windows 8.1 mobile device, can become upgraded to Microsoft Windows 10. You might need to free up additional space if your device is eligible. Also, you may need to install additional update(s) before proceeding with a Microsoft Windows 10 mobile upgrade.
This Microsoft Windows 10 upgrade adviser will notify you if there is a Windows 10 update available. If there is an update available, you want to go to your phone’s “Settings” and choose “Phone Update”. If a Microsoft Windows 10 upgrade is available you should be able to download and proceed with the upgrade.
There might be more than one build that needs to download and install. Finally, you can check your carrier if a Microsoft Windows 10 upgrade is not yet available. They may have a dedicated web page letting you know a time table of future updates.