Lesson33- how to debug KC868-A8S GSM module using AT command

[alexanderhez]

HardwareSerial.cpp  define serial port pins:
#ifndef RX2
#define RX2  15
#endif

#ifndef TX2
#define TX2  13
#endif

hello, thank you for help ous.
please if can explain or make code for receive text message  
+CMTI: "SM",1    display receive information
AT+CMGR=1        read No.1 SMS
AT+CMGL="ALL"  read all SMS
AT+CMGD=1        delete No.1 SMS
AT+CMGD=1,4    delete all SMS