SOURCE CODE :
#include <SoftwareSerial.h>
SoftwareSerial sim(3, 2);
int _timeout;
String _buffer;
String number = “+91xxxxxxxxxx”; //-> change with your number
void setup() {
delay(7000); //delay for 7 seconds to make sure the modules get the signal
Serial.begin(9600);
_buffer.reserve(50);
Serial.println(“System Started…”);
sim.begin(9600);
delay(1000);
Serial.println(“Type s to send an SMS, r to receive an SMS, and c to make a call”);
}
void loop() {
if (Serial.available() > 0)
switch (Serial.read())
{
case ‘s’:
SendMessage();
break;
case ‘r’:
RecieveMessage();
break;
case ‘c’:
callNumber();
break;
}
if (sim.available() > 0)
Serial.write(sim.read());
}
void SendMessage()
{
//Serial.println (“Sending Message”);
sim.println(“AT+CMGF=1”); //Sets the GSM Module in Text Mode
delay(1000);
//Serial.println (“Set SMS Number”);
sim.println(“AT+CMGS="+91xxxxxxxxxx"”); //Mobile phone number to send message
delay(1000);
String SMS = “Hello, how are you?”;
sim.println(SMS);
delay(100);
sim.println((char)26);// ASCII code of CTRL+Z
delay(1000);
_buffer = _readSerial();
}
void RecieveMessage()
{
Serial.println (“SIM800L Read an SMS”);
delay (1000);
sim.println(“AT+CNMI=2,2,0,0,0”); // AT Command to receive a live SMS
delay(1000);
Serial.write (“Unread Message done”);
}
String _readSerial() {
_timeout = 0;
while (!sim.available() && _timeout < 12000 )
{
delay(13);
_timeout++;
}
if (sim.available()) {
return sim.readString();
}
}
void callNumber() {
sim.print (F(“ATD”));
sim.print (number);
sim.print (F(“;\r\n”));
_buffer = _readSerial();
Serial.println(_buffer);
}
OUTPUT :
System Started…
Type s to send an SMS, r to receive an SMS, and c to make a call
+CMGS: 137(When ‘s’ is pressed)
OK
SIM800L Read an SMS(when 'r ’ is pressed)
Unread Message doneAT+CNMI=2,2,0,0,0
OK
+CMT: “+91xxxxxxxxxx1”,“”,“19/09/07,15:05:06+22”
Hi arduino
ATD+91xxxxxxxxxx;(when ‘c’ is pressed)
OK
NO CARRIER
Can you please help me rectify the error