Send Special Characters Via SMS

Official Hardware Retired GSM Shield
2

Hi, you can send whatever ASCII character with:

#include <GSM.h>

#define PINNUMBER ""

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

char txt[8] = {'{', 'H', 'e', 'l', 'l', 'o', '}', 0}; // TXT: {Hello}\0

void setup()
{
  // initialize serial communications and wait for port to open:
  Serial.begin(9600);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for Leonardo only
  }
  
  // connection state
  boolean notConnected = true;

  // Start GSM shield
  // If your SIM has PIN, pass it as a parameter of begin() in quotes
  while(notConnected)
  {
    if(gsmAccess.begin(PINNUMBER)==GSM_READY)
      notConnected = false;
    else
    {
      Serial.println("Not connected");
      delay(1000);
    }
  }
  
  Serial.println("GSM initialized");
}

void loop()
{
    // send the message
  sms.beginSMS("+34123456789"); // Telephone Number
  sms.print(txt); // Content
  sms.endSMS(); 
  Serial.println("\nCOMPLETE!\n");
}