Hi Arduino users.
I have a problem on my GSM SIM 900 at the moment.
I use GSM SIM 900 with my arduino UNO, my problem is I did not received any message on my handset, I think I did not have any mistake on my connection of the circuit. Anyone can help me?

This is what I want my project work :-

Press the button, SMS will send to my phone.

I have connect my push button to pin 3 arduino.
LED to pin 13
TX GSM SIM 900 to RX (pin 7) arduino
RX GSM SIM 900 to TX (pin 8) arduino

below is my arduino code:-

#include <SoftwareSerial.h>

SoftwareSerial mySerial(7, 8); // RX, TX pins

void setup() {

pinMode(13, OUTPUT); // Initialize pin 13 as digital out (LED)
pinMode(3, INPUT); // Our button pin
mySerial.begin(4800); // Open serial connection at baud rate of 4800


void loop(){

if (digitalRead(3) == HIGH){ // On button press
digitalWrite(13, HIGH); // Turn LED on.
mySerial.println(“AT”); // Sends AT command to wake up cell phone
mySerial.println(“AT+CMGF=1”); // Puts phone into SMS mode
delay(1000); // Wait a second
mySerial.println(“AT+CMGW=”+447784101249""); // YOUR NUMBER HERE; Creates new message to number
mySerial.print(“Sent from my Arduino.”); // Message contents
mySerial.write(byte(26)); // (signals end of message)
mySerial.println(“AT+CMSS=1”); // Sends message at index of 1
digitalWrite(13, LOW); // Turn LED off
digitalWrite(13, HIGH); // Turn LED on.
delay(10000); // Give the phone time to send the SMS
mySerial.println(“AT+CMGD=1”); // Deletes message at index of 1
digitalWrite(13, LOW); // Turn LED off.


In my limited recent experience with these...isnt the gsm baud rate 19200 by default?
are the serial links on the GSM set to look at a software serial port or the hardware pins?
CR at end of command string.
is the software reset pin used in your hardware.
serial buffer lenght setting.

These were the items i had wrong when i had a simmilar issue to you

I have a problem on my GSM SIM 900 at the moment.

Which one? Link?