Unicom's mobile phone card sends text messages to mobile. Why can't the other party receive it?

Unable to 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 it is still not received after deletion, you can change the machine or card to see if it is a hardware factor; 3. After eliminating the above reasons, try to see if 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 Unicom's manual customer service to handle this problem.