Apple's mobile phone can't receive the verification message from the external network.

1. First, click Settings to open the message and see if the option of IMESSAGE message is turned on. If it is not open, click the slider on the right to open it. In addition, if the mobile phone can't receive the verification code, there may be a problem with the network.

Secondly, you can turn on the flight mode in the settings and turn it off after a few seconds.

3. Finally, if you still can't receive the verification code, you can try to restart the phone to solve it.