How does Unicom check traffic with SMS?

Hello, 3G users can send CXLL (case-insensitive) or 107 1 to 100 10 to inquire about the usage of charged traffic in the previous month in Japan. Use this machine to edit the short message "CXZLL" to 100 10 to inquire about the total traffic usage of users as of the previous day. You can also log in to the client of China Unicom's mobile phone business hall or contact Unicom's customer service with the contact number.