Why can't Unicom's mobile phone card receive the verification code sent?

Unicom users can't receive SMS or verification code for 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 problems do not exist, please contact customer service to verify.