What is the reason why Apple's 4s Unicom 4g card can't receive SMS?

You can't receive SMS or verification code due to the following reasons:

1, you can check whether the mailbox is full first. If it is full, please delete some information.

2. If you still can't get it after deleting it, you can change the machine or card to see if it is a hardware factor.

3. After eliminating the above reasons, you can try to test whether it can be received in other places to see if it is the reason for the weak local signal.

If the above problem does not exist, please contact the local manual customer service to handle this problem.