Cell phone hack

I made progress on the cell phone hacking project. The basic concept was to be able to use a cellphone instead of a cellular shield with the Arduino to send text messages via serial.

First things first I needed to find out how the cellphone (I bought a Motorola AND  Sim card )would communicate with the Arduino via the TTL serial port of the phone which is just located in the headset jack on the top of the phone. The phone uses and is controlled using AT Commands (Here is a very helpful website about AT commands).  

I just used a TRS headset plug that I bought from Amazon (here is the link) compatible with the cellphone to make the connection between the Phone and the Arduino.

I soldered a wire to each of the three connectors on the TRS plug. I used the Tip connector as the TX connection (going to the Arduino), the ring connector as the RX connection and finally the sleeve connector as the ground.

 

                                                        Balanced TRS cable

Once the wires were soldered on the TRS, it just became a matter of connecting everything together. So I plugged in the TRS cable in the headset jack of the phone  and used the soldered wires to go on the arduino ( pins 2 and 3) which can be seen below in the fritzing schematic.

Testing

So to test this out I plugged in the headset , pushed the button and waited to receive the message on my cellphone.

The code I used to test this out was pretty basic. I used the Arduino’s software library to set up a software serial connection on pins 3 and 2 ( RX and TX  pins). Due to excessive power management of the phone It was required to send something over the serial connection to wake the phone up first and then put it in text mode.  Naturally, after that I just created my text message (from the code) and send it to my number then deleted the message from the phone’s outbox after it’d been sent.

#include <SoftwareSerial.h> SoftwareSerial mySerial(3,2); // my pins 2 and 3 I used as RX, TX void setup() { pinMode(13, OUTPUT); // pin 13 digital out pinMode(8, INPUT); // pushbutton mySerial.begin(4800); // serial connection baud rate 4800 } void loop(){ if (digitalRead(8) == HIGH){ // If button pressed digitalWrite(13, HIGH); // LED on. mySerial.println("AT"); // wake up cell phone (Send AT command) delay(1000); //  wait a second mySerial.println("AT+CMGF=1"); //phone goes in text mode delay(1000); mySerial.println("AT+CMGW=\"+1413645####\""); // destination number delay(1000); mySerial.print("testing out my arduino cellphone ."); // message composed delay(1000); mySerial.write(byte(26)); // (signals end of message) delay(1000); mySerial.println("AT+CMSS=1"); // message sent digitalWrite(13, LOW); // LED off delay(250); digitalWrite(13, HIGH); // LED on. delay(10000); // wait for the phone to send mySerial.println("AT+CMGD=1"); // Deletes message after reception digitalWrite(13, LOW); // LED off. delay(250); } }

Useful link : 

http://www.developer.nokia.com/Community/Wiki/Using_AT_commands_to_send_and_read_SMS