#include <SoftwareSerial.h>
SoftwareSerial SIM900A(8,7);
void setup()
{
  SIM900A.begin(115200);   // Setting the baud rate of GSM Module
  Serial.begin(9600);    // Setting the baud rate of Serial Monitor (Arduino)
  Serial.println ("SIM900A Ready");
  delay(100);
  Serial.println ("Type s to send message or r to receive message");
  delay(15000);
  SendMessage();
}
void loop()
{

  if (Serial.available()>0)
   switch(Serial.read())
  {
    case 's':
      SendMessage();
      break;
    case 'r':
//      RecieveMessage();
      break;
  }
 if (SIM900A.available()>0)
   Serial.write(SIM900A.read());

}
 void SendMessage()
{
  Serial.println ("Sending Message");
  SIM900A.println("AT+CMGF=1");    //Sets the GSM Module in Text Mode
  delay(1000);
  Serial.println ("Set SMS Number");
  SIM900A.println("AT+CMGS=\"+9665********\"\r"); //Mobile phone number to send message
  delay(1000);
  Serial.println ("Set SMS Content");
  SIM900A.println("Good 123?");// Messsage content
  delay(100);
  Serial.println ("Finish");
  SIM900A.println((char)26);// ASCII code of CTRL+Z
  delay(1000);
  Serial.println ("Message has been sent ->SMS Selesai dikirim");
}