If your mobile phone is not Chinese mainland's mobile phone number, you will not receive the verification code; Currently, only Chinese mainland mobile phone number registration is supported. We suggest that you register a new mobile phone number. Mobile phone security software intercepts short messages. Please turn on the mobile phone security software, temporarily turn off the interception function, and then try to get the verification code again.
The SMS gateway is congested or abnormal. If the SMS gateway is congested or abnormal, you will not be able to receive SMS. In this case, it is recommended to wait for a period of time to resend the verification code.
People around you can use it normally, but they can't get it themselves. This may be the reason of the mobile phone itself. It is suggested to test the switch card, change your mobile phone card to someone else's mobile phone to receive short messages, and try again.
Sending SMS verification frequency is too fast. Because you send verification messages too frequently, I suggest you try again after a while.
CAPTCHA is the abbreviation of "automatic public Turing test to distinguish between computer and human", and it is a public * * * automatic program used to distinguish whether the user is a computer or a human. It can prevent malicious password cracking, ticket brushing and forum flooding, and effectively prevent a hacker from constantly trying to log in to a specific registered user and using a specific program to violently crack. In fact, using verification code is a popular way for many websites now, and we have realized this function in a relatively simple way. This question can be generated and judged by computers, but only humans can answer it. Because the computer can't answer CAPTCHA's question, the user who answers the question can be considered as human.
Reference link: verification code-Baidu Encyclopedia