How to view the content of SMS with the A6 module?

I try to send a message from my cell phone to the module so that it appears on the screen and at the same time (depending on the case), turn on or off a led, but instead of the message I sent I get <+ CIEV: "SMSFULL ", 2> in addition to the fact that the led does nothing.

I leave the code:

/ *
 ************* WORKING WITH THE A6 MODULE *****************
 * /
#include <SoftwareSerial.h>

String PHONE = ""; // For multiple users
String msg;

// Pin RX del módulo a Arduino 9
// Pin TX del módulo a Arduino 8
#define rxPin 9     
#define txPin 8     

SoftwareSerial mySerial(txPin, rxPin);

#define LED_PIN 13

void setup() {
  pinMode(LED_PIN, OUTPUT); // Configuration of pin 13 as output
  digitalWrite(LED_PIN, LOW);
  delay(1000);

  Serial.begin(115200);
  Serial.println("Initializing Serial... ");

  mySerial.begin(115200);
  Serial.println("Initializing GSM module...");
  
  mySerial.println("AT+CMGF=1\r"); //SMS text mode
  mySerial.println("AT+CNMI=1,2,0,0,0");  
  delay(1000);
}

void loop()
{
  while (mySerial.available())
  {
    parseData(mySerial.readString());//Call the parseData function to parse SMS
  }
  doAction(); //Take the necessary action according to the SMS message
  while (Serial.available())
  {
    mySerial.println(Serial.readString()); 
  }

}

void parseData(String buff) 
{
  Serial.println(buff);

  unsigned int index;

  //Remove the "AT Command" sent from the reply string.
  index = buff.indexOf("\r");
  buff.remove(0, index + 2);
  buff.trim();

  if (buff != "OK") 
  {
    index = buff.indexOf(":");
    String cmd = buff.substring(0, index);
    cmd.trim();
    
    
    buff.remove(0, index + 2);

    // Parse the required message from the serial buffer string
mySerialL
    if (cmd == "+CMT") 
    {
      
      // get the newly arrived memory location and store it in temp
      index = buff.lastIndexOf(0x0D);// Buscando posición de CR (retorno)
      msg = buff.substring(index + 2, buff.length());// Write the message in the variable "msg"
      msg.toLowerCase();//The entire message is changed to lowercase
      Serial.println(msg);
      
      index = buff.indexOf(0x22);// Looking for the position of the first double quotes-> "
      PHONE = buff.substring(index + 1, index + 14); // Write the phone number in the variable "PHONE"
      Serial.println(PHONE); 
      
    }
  }
}

void doAction()
{
 
  if (msg == "led on")
  {
    digitalWrite(LED_PIN, HIGH);
    Reply("LED is ON");
    Serial.println("Did the led turn on?");     
  }
  else if (msg == "led off")
  {
    digitalWrite(LED_PIN, LOW);
    Reply("LED is OFF");
    Serial.println("Did the led turn off?");    
  }

  PHONE = "";// Delete the string from the phone
  msg = "";// Delete the message string
}

void Reply(String text)
{
  mySerial.println("AT+CMGF=1\r");
  delay(1000);
  mySerial.println("AT+CMGS=\"" + PHONE + "\"\r");
  delay(1000);
  mySerial.println(text);
  delay(100);
  mySerial.write(0x1A); // código ascii para ctrl + z, DEC-> 26, HEX-> 0x1A
  delay(1000);
  Serial.println("SMS Sent Successfully.");
}