The reason why SMS can't be delivered.

Reason 1: This situation may be that the other party's mobile phone stopped due to arrears, resulting in the information not reaching the other party's mobile phone.

Solution: After paying the phone bill in the business hall, you can successfully send short messages by turning on your mobile phone.

Reason 2: If the other party is turned off or out of service for a long time, the information can only be kept in the center for 48 hours and then the information will be invalid.

Solution: Find a way to tell the other party to turn it on.

Reason 3: The SMS inbox of the other party is full, and the SMS cannot arrive.

Solution: You can tell the other person to clean up the inbox.