GSM GPRS SIM900A Modem- Arduino Compatible

/*
* Project name:
GSM GPRS SIM900A Modem- Arduino Compatible
* Copyright
(c) Researchdesignlab.com
* Description:

* Test configuration:
MCU: ATMEGA328
Dev.Board: Arduino uno
Oscillator: 16 MHz
Software: Arduino

*/

const int SensorPin = 2; // the number of the pushbutton pin
const int Power_Key = 9;

int SensorState = 0;
int rec;
void setup() {
pinMode(Power_Key, OUTPUT);
digitalWrite(Power_Key, LOW);
pinMode(SensorPin, INPUT);

Serial.begin(9600);


}

void loop() {
SensorState = digitalRead(SensorPin);

if (SensorState == HIGH)
{
digitalWrite(Power_Key, HIGH);
delay(1000);
digitalWrite(Power_Key, LOW);
rec=0;

while(rec!='C')
{
while(!Serial.available());
rec=Serial.read();
}
rec=0;
while(rec!='a')
{
while(!Serial.available());
rec=Serial.read();
}
rec=0;
while(rec!='l')
{
while(!Serial.available());
rec=Serial.read();
}
rec=0;
while(rec!='l')
{
while(!Serial.available());
rec=Serial.read();
}
Serial.println("AT");
delay(1000);
Serial.println("AT+CMGF=1");
delay(1000);
Serial.println("AT+CMGS=\"9986431377\""); //CHANGE TO DESTINATION NUMBER
delay(1000);
Serial.print("Sensor Activated");
Serial.write(26);
rec=0;
while(rec!='K')
{
while(!Serial.available());
rec=Serial.read();
}
delay(1000);
digitalWrite(Power_Key, HIGH);
delay(1000);
digitalWrite(Power_Key, LOW);
delay(1000);
}

}