Sim 900, message control?/ call control ?

Hi, I have to control UNO using sim 900 shield,

pls help me to write program If I send the message it should not do anything while receiving next message. After receiving next message It have to go for void loop and have to do something.

Exactly I need button read should not work if send the message 'Off'

while I send the message 'On' like that. Thank u

I need to work on this program/*
Button

Turns on and off a light emitting diode(LED) connected to digital
pin 13, when pressing a pushbutton attached to pin 2.

The circuit:

  • LED attached from pin 13 to ground

  • pushbutton attached to pin 2 from +5V

  • 10K resistor attached to pin 2 from ground

  • Note: on most Arduinos there is already an LED on the board
    attached to pin 13.

created 2005
by DojoDave http://www.0j0.org
modified 28 Oct 2010
by Tom Igoe

This example code is in the public domain.

*/

// constants won't change. They're used here to
// set pin numbers:
const int buttonPin = 2; // the number of the pushbutton pin
const int ledPin = 13; // the number of the LED pin

// variables will change:
int buttonState = 0; // variable for reading the pushbutton status

void setup() {
// initialize the LED pin as an output:
pinMode(ledPin, OUTPUT);
// initialize the pushbutton pin as an input:
pinMode(buttonPin, INPUT);
}

void loop(){
// read the state of the pushbutton value:
buttonState = digitalRead(buttonPin);

// check if the pushbutton is pressed.
// if it is, the buttonState is HIGH:
if (buttonState == HIGH) {
// turn LED on:
digitalWrite(ledPin, HIGH);
}
else {
// turn LED off:
digitalWrite(ledPin, LOW);
}
}