What can Unicom send to check the balance and residual flow by SMS?

Write a short message "CXLL" (that is, the pinyin initials for inquiring traffic) and send it to 100 10. Wait a moment, the system will reply a short message, informing it of the remaining network traffic and other information at the current number. To check the available balance, just write a short message "10 1" and send it to 100 10 without any charge.