how i can add small modification to control relay in GSM receive SMS

how i can add small modification to control relay in GSM receive SMS

// include the GSM library
#include <GSM.h>

// PIN Number for the SIM
#define PINNUMBER ""

// initialize the library instances
GSM gsmAccess;
GSM_SMS sms;

// Array to hold the number a SMS is retreived from
char senderNumber[20];

void setup() {
// initialize serial communications and wait for port to open:
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for native USB port only
}

Serial.println("SMS Messages Receiver");

// connection state
boolean notConnected = true;

// Start GSM connection
while (notConnected) {
if (gsmAccess.begin(PINNUMBER) == GSM_READY) {
notConnected = false;
} else {
Serial.println("Not connected");
delay(1000);
}
}

Serial.println("GSM initialized");
Serial.println("Waiting for messages");
}

void loop() {
char c;

// If there are any SMSs available()
if (sms.available()) {
Serial.println("Message received from:");

// Get remote number
sms.remoteNumber(senderNumber, 20);
Serial.println(senderNumber);

// An example of message disposal
// Any messages starting with # should be discarded
if (sms.peek() == '#') {
Serial.println("Discarded SMS");
sms.flush();
}

// Read message bytes and print them
while (c = sms.read()) {
Serial.print(c);
}

Serial.println("\nEND OF MESSAGE");

// Delete message from modem memory
sms.flush();
Serial.println("MESSAGE DELETED");
}

delay(1000);

}

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Which GSM library are you using?

Which SMS receiving device are you using?

Does the code you have posted work?