What they said is too complicated. I will teach you the simplest method. Mijing 92702689 well, check the total timer of the mobile phone. If you want to buy a new mobile phone, you can use this. If it is not used, it will display 000000:00! ,,,,,then press *#06#, then a serial number will appear for you on your phone, you can count to the seventh and eighth numbers.

If your seventh and eighth numbers are the corresponding two numbers below, then the quality of your mobile phone is determined.

0, 2 or 2, 0, is a very bad mobile phone

0, 8 or 8, 0, is a better mobile phone

0, 1 or 1, 0, it is a very good mobile phone

0, 0 means it is produced by the original company and is the best quality mobile phone (original mobile phone)

1, 3 means it is It is produced in Azerbaijan and is a very, very poor mobile phone

Try it! Good luck to you.