GSM GPRS for sending an sms I want to know if it is possible to send an SMS from a SIM900 using Arduinos to another SIM900.

Problem: When the gsm is connected to the network, it does not send an sms; my airtime balance remains the same.

Here is the code I used:

#include &lt;SoftwareSerial.h&gt;
SoftwareSerial SIM900 (9,10);

void setup()
{
   serial.begin(9600);
   SIM900.begin(9600);
   delay(5000);
}

void loop()
{
   sendSMS();

   while(SIM900.available()!=0)
     {
        Serial.println(SIM900.read());
     }
}

void sendSMS()
{
    SIM900.println("AT+CMGF=1\r");
    delay(100);
    SIM900.println("AT+CMGS=\"+27769384488"\r");
    delay(100);
    SIM900.println("Hello");
    delay(100);
    SIM900.println((char)26);
    delay(100);
    SIM900.println();
    delay(5000);

}
Yes, it is possible.

Your code doesn't show any sign of board powering on and initialization.

SIM900 has some LED that show status - make sure you are connected to GSM network.

Please check this tutorial: https://www.youtube.com/watch?v=RUGV_64lQX8