If the SMS failed to be sent, please try again. Actually, I can't send my message after I receive it. I went to the mobile phone business hall a few days ago and I don't know why I can't send it again

If the SMS failed to be sent, please try again. Actually, I can't send my message after I receive it. I went to the mobile phone business hall a few days ago and I don't know why I can't send it again. If you use Unicom number, you can't send SMS for the following reasons:

1, abnormal status of mobile phone number (shutdown, sold number, etc.). );

2. The SMS center number is wrong;

3. The SMS function of the mobile phone card is not enabled;

4. Send a large number of short messages in a short time;

It is suggested to eliminate the above reasons. If you still have questions, you can contact the local Unicom customer service consultation.