1

This question already has an answer here:

Windows 10 on lumia phones are eye catching. But my old lumia 625 didn't get any official update. Is their any way to update without getting any official update like we can do in android phones?

marked as duplicate by Manuel Durando, Nirav Madariya, Thomas, Indrek, Neil Turner Apr 27 '16 at 15:39

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

3

You can download and install the insider preview if you want to.

But your phone is not on the currently supported list for Insider preview. So you may not get future insider builds or updates. It's better to stay in Windows Phone 8.1

See : Supported phones for Windows 10 Mobile Insider Preview

If you want to install Windows 10 insider preview anyway follow these steps:

  1. Register as a Windows Insider in here
  2. Download the Windows Insider app on your phone
  3. Launch the app and log in with the Microsoft account registered in the Insider website
  4. Choose how often you want to receive new builds. I recommend production ring or slow ring as they will have fewer bugs.

Not the answer you're looking for? Browse other questions tagged or ask your own question.