Being somewhat of a hacker at heart, it was only a matter of time until I decided to jailbreak my new iPhone. I know that it invalidates my warranty, but I liked the idea of some of the cool tools I could download, which aren’t available through the iTunes store. Plus – it’s my phone, so if I break it I’ve only got myself to blame! Jailbreaking the phone – a term for removing the restriction to only download software approved by Apple – was a bit of a paradoxical exercise. It was simultaneously easier, and more difficult, than I thought!

My iPhone is a 3G, running operating system version 3.1.3, and baseband 05.12.01. I should stress that jailbreaking is not unlocking. Unlocking the phone appears to be difficult with the 05.12.01 baseband and, although methods for doing this can be found on the Internet, it wasn’t what I wanted to do. If you want to jailbreak your iPhone then, firstly, make backups and make sure you can restore it later. I’m not accepting any responsibility for what happens if you follow these instructions. It worked for me – it may not work for you!

In another seemingly contradictory situation, you will have to run this hack from a Windows computer. Thanks Apple!!

Firstly, I’d recommend that you download the recovery firmware in case you need it! For version 3.1.3 (7E18), it can be downloaded from Apple here for the 2G; here for the 3G and here for the 3GS. When I downloaded it, the file automatically downloaded as a zip file. If it does the same for you, just rename the file after downloading – changing the extension from “.zip” to “.ipsw”.

Download the latest version of iTunes and backup and sync your iPhone. You now have all the tools necessary to recover your iPhone if something goes wrong.

My first attempt at jailbreaking was a complete disaster. I tried the “sn0wbreeze” method, which simply didn’t work. My iPhone would not restore the jailbroken firmware, and I ended up restoring the default, downloaded firmware – losing all my saved SMS messages in the process.

The second attempt was successful. I used an app called Spirit, which can be downloaded from here for Windows or for Mac. The process is very simple:

1. Connect your iPhone via USB, then backup and sync it
2. Run Spirit
3. Click the Jailbreak button
4. Wait for the app to display Jailbreak succeeded! The iPhone will reboot and Cydia will be installed.

Jailbreak iPhone with Cydia installed

If something goes wrong, and your iPhone doesn’t restart, then you can restore it using the firmware you downloaded earlier, and the backup.

1. Switch off the iPhone, then put it in Recovery mode by holding down the Home button as you connect the USB cable to the computer.
2. Click on the iPhone in the left hand pane of iTunes
3. Hold down the left shift key on your computer and click on the Restore button, iTunes will prompt you to locate the firmware.
4. Browse to the file we renamed to the  ”.ipsw” extension earlier, and your firmware will be restored.
5. Now right click on the iPhone in iTunes and choose Restore from backup. If you’re using the latest version of iTunes, this will restore all your apps, settings, contacts and text messages.

Now that my iPhone has been successfully jailbroken (is that a word??), I’m enjoying looking round the underlying Linux-like environment and hacking away at some command line tools.

UPDATE: I’ve since tried jailbreaking both a 16Gb and a 32Gb iPhone 3GS using this method, and it worked flawlessly.