How to check the remaining number of SMS messages in one month?

In fact, mobile companies now have corresponding query methods. Just send "BYLCX" (the first letter of "monthly inquiry") to "10086", and the other party will reply to you by SMS, telling you the number of SMS messages per month, GPRS traffic, MMS messages per month and so on. And this function is free (sending text messages is only 10 cents). Very convenient.