Receiving SMS by GSM

Hi, I am using ATK-GSM SIM900A. My GSM Sends the message to the mobile but cannot receive the message sent from the mobile. The code i used is. The programming Language is #C++

// Example 55.4

#include <SoftwareSerial.h>
SoftwareSerial SIM900(0, 1);

char incoming_char=0;

void setup()
{
Serial.begin(19200); // for serial monitor
SIM900.begin(19200); // for GSM shield
SIM900power(); // turn on shield
delay(20000); // give time to log on to network.

SIM900.print(“AT+CMGF=1\r”); // set SMS mode to text
delay(100);
SIM900.print(“AT+CNMI=2,2,0,0,0\r”);
// blurt out contents of new SMS upon receipt to the GSM shield’s serial out
delay(100);
}

void SIM900power()
// software equivalent of pressing the GSM shield “power” button
{
digitalWrite(9, HIGH);
delay(1000);
digitalWrite(9, LOW);
delay(7000);
}

void loop()
{
// Now we simply display any text that the GSM shield sends out on the serial monitor
if(SIM900.available() >0)
{
incoming_char=SIM900.read(); //Get the character from the cellular serial port.
Serial.print(incoming_char); //Print the incoming character to the terminal.
}
}

You have no need to use SoftwareSerial on pins 0 & 1 as they already have a hardware serial connection. And they are used by Serial to connect to the Serial Monitor, so using them to communicate with the modem too isn't going to work too well.

Could you provide a link to the modem you are using?