How does Century Tiancheng account know what mobile phone it is bound to?

Your mobile phone numbers are all your own. Try to change your password or secret protection. It needs to be verified, which should allow you to receive and send short messages. You must remember the password of your account and the secret protection of your mobile phone number. Tiancheng customer service will basically not do anything for you, just telling you that I am still alive and the game is not yellow.