Hello, I work with a SIM800l, and this gives me a little problem with sending messages to another phone number, my code is this, I extract the phone number with "substring ()", the problem is not in the shipment, Since the messages to my phone arrive perfectly, the problem is when another phone sends a message, it does not receive anything, and on the arduino serial monitor it tells me that the SMS was sent correctly
if (SIM.available()) {
Comando = SIM.readString();
Serial.println(Comando);
Numero = Comando.substring(9,20);
Serial.println(Numero);
if (Comando.indexOf(Clave) >= 0){
SMS("Recivido correctamente");
Comando = "";
}else{
SMS("ERROR: Clave y/o Comando incorrectos");
}
}
//Serial.println("esperando comando");
delay(250);
//updateSerial();
}