Download SMS Spy Backup Apk Android App to your mobile phone and tablets from Android Mobile Zone.
SMS spy help to save all your incoming sms messages to txt file.
1.install application on your device
2. After run the application hides its icon
3. prefer file name and folder
4. put your mobile number that will be used to run the application (don't forget it must set number)
5. then run application and just dial the number
When a device get a SMS, its content, sender number, name and date will be saved in logfile.
PS: the default number - 123654
PPS: ROOT is not needed