How to back up SMS for OS flash in smartphone

How to retrieve your SMSs even after flashing your Android phone. The tips expressed from our experts should be helpful for you.

I would like to flash the Android operating system due to stuck / hang issue in my smartphone. I wanted to save the old SMS and retrieve it back after mobile phone flash or restore factory setting. Thus, I would like to know how to keep and retrieve the old SMS stored by default in Android smartphone even after its flash? Kindly enlighten on this.