serial 1 was not declared in the scope

#include <LiquidCrystal.h>
LiquidCrystal lcd(2, 3, 4, 5, 6, 7);
#include <SoftwareSerial.h>


char Mob[20]="+923319020922";
String stringGPS = "";
String stringGPS1 = "";
char c=0;
int t=0,i;
int buzzer = 9;
int buttonState = 0;

SoftwareSerial mySerial(10, 11); // RX, TX

//const int buttonPin1 =9 ;
int buttonState1 = 0;
int helmetstate=0;
const int relay=8;
char inByte=0;

void setup() 
{
  lcd.begin(20, 4); 
  lcd.setCursor(0, 0);
  pinMode(relay, OUTPUT);
  pinMode(buzzer, OUTPUT);
  Serial.begin(9600);
  Serial1.begin(9600);
  Serial2.begin(9600);
  digitalWrite(relay, LOW);
  delay(15000); 
  lcd.print("Config modem...."); 

  Config(); 

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Smart helmet      ");
}

void loop()
{
  if(Serial2.available())
  {
    inByte = Serial2.read();  
    //Serial.write(inByte);
    if(inByte=='A'||inByte=='B'||inByte=='C'){
    inByte=0;
    SMS(Mob);

    while(Serial2.available()>0)
    {
      i = Serial2.read();
    }
  }

  if(inByte=='D')
  {
    digitalWrite(relay, LOW);
    inByte=0;
  }

  if(inByte=='E')
  {
    digitalWrite(relay, HIGH);
    inByte=0;
  }
  else 
  {
  }
} 

 //buttonState = digitalRead(buttonPin);  
 // if (buttonState == LOW) {
 //Serial.print("ok");
 //lcd.clear();
 // lcd.setCursor(0, 0);
 //lcd.print("Sending msg       ");
 // lcd.setCursor(0, 0);
 //lcd.print("Smart helmet      ");
 // checkGPS();
 // SMS(Mob);

 //helmet();
 checkGPS(); 
 lcd.setCursor(0, 1);
 lcd.print(stringGPS1); 
 //Serial.println(stringGPS1);
}

/*
void helmet()
{
  buttonState1 = digitalRead(buttonPin1);
  if (buttonState1 == HIGH) 
  {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("SWITCH ON  .......    "); 
    digitalWrite(relay, HIGH);
  }
  else 
  {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("SWITCH OFF .......    "); 
    digitalWrite(relay, LOW);
  }
}
*/

void checkGPS()
{
  // Serial.print("check gps");
  // while (Serial.available()) 
  // {
  if (Serial.available()>0)
  {
   // c = Serial.read();        
   // stringGPS  = c;
   //Serial.print(c);
   while (c != 'R') 
   {
     c = Serial.read();
     // Serial.print(c);
   }
    // if (c== 'R')
    // {
    //   Serial.print(c );
         while(t!=41)
         {
           if (Serial.available())
           {
             c = Serial.read(); 
             stringGPS += c;
             t++;
             //Serial.print(stringGPS );
          }
  }
  stringGPS1= stringGPS.substring(15, 41);
  // Serial.println(stringGPS1);
  t=0;
  c=0;
  stringGPS = "";
    // }
  }
  }

void SMS(char Mob[20])
{
   digitalWrite(buzzer, HIGH);
   lcd.setCursor(0, 0);
   lcd.print("Sending msg       ");
   Serial1.print("AT+CMGS="");     // send the SMS number
   Serial1.print(Mob);/// Send mobile number
   Serial1.print(""r");
   delay(4000);  
   Serial1.print(stringGPS1);// send the SMS Data
   Serial1.print("r");
   delay(2000);
   Serial1.write(0x1A);  ///Ctrl+Z  
   delay(1000);
   Serial1.write(0x0A);  ///Carrige return   
   delay(1000);
   Serial1.write(0x0D);    ///line feed 
   delay(1000);
   stringGPS1 = "";
   lcd.setCursor(0, 0);
   lcd.print("Smart helmet      ");
   digitalWrite(buzzer, LOW);    
}

void Config()/////configuration for sim900 
{
  delay(4000);
  Serial1.print("ATE0r"); ////Disable Echo
  delay(4000);
  Serial1.print("ATr"); ///checking echo
  delay(4000);
  Serial1.print("AT+CMGF=1r");///msg format
  delay(4000);     
}

when i run this code it give me error that serial1 was not decleared in the scope