This is a guide geared towards iPhone users with Mac OS X. The steps are exactly same as they are on a Windows system. You can find the Windows version of the guide here.
For those of you who don’t know, yesterday Apple pushed a new firmware update for all iPhone and iPod touch users which brought some important security and bug fixes. Features wise, there was nothing new to be seen in the firmware. Since this firmware updates the baseband to 05.12.01 on iPhone 3GS and 3G, therefore you are required NOT to update to this firmware if you want to preserve your unlock on iPhone 3G and iPhone 3GS. It will also NOT work with iPod touch 2G(new MC models) and iPod touch 3G. The only devices which can be currently jailbroken using redsn0w 0.9.x is iPhone 2G and iPod touch 1G/2G(older non-MC models).
Follow the steps below to jailbreak your device on iPhone 3.1.3 only if you have iPhone 2G, iPod touch 1G/2G(older non-MC models). iPhone 3G can also be jailbroken but then you will lose your unlock (perhaps forever). So jailbreak your iPhone 3G only if you have a supported SIM like that of AT&T in US and O2 in UK.
Note: In this guide I have used redsn0w 0.9.4. If this version gives you problem on iPhone 2G and iPod touch 1G, then try redsn0w 0.9.3. Download redsn0w 0.9.3 from here and then follow the instructions as follows.
Step 1: Update to original iPhone 3.1.3 firmware via iTunes. Downloading and installation instructions for iPhone 3.1.3 firmware can be found from here.
Step 2: Start redsn0w 0.9.4 and point it to the respective original iPhone 3.1.2 firmware to proceed. Yes you need to point it to iPhone 3.1.2 instead of 3.1.3 because redsn0w 0.9.4 is still unable to validate the latest firmware.
Step 3: Now select “Install Cydia”, “Unlock” and “Already pwned” options for iPhone 2G. If you are using iPod touch 1G/2G(older non-MC models) then simply select “Install “Cydia” to continue.
Step 4: Now make sure your device is both OFF and PLUGGED IN to the computer before you click “Next”.
Step 5: Connect your device in recovery mode by pressing the Power and buttons continuously.
At this stage you will be presented with a screen where you will have to quickly hold “Power” button and then while holding the “Power” button, you will now have to hold “Home” button too. Now after few seconds release “Power” button but keep holding “Home” button until installation begins.
Step 6: Sit back and enjoy while redsn0w will do all the rest for you. Once done, your iPhone 2G/iPod touch 1G/2G(older non-MC model) will restart automatically and you will find it jailbroken with iPhone firmware version 3.1.3.
Unlock for iPhone 2G Only
Step 7: Once you are done with the jailbreak, you can now unlock your iPhone 2G running jailbroken firmware 3.1.3 by using BootNeuter app from Cydia. Follow the instructions from Step 4 here to unlock iPhone 2G on 3.1.3 firmware.
Disclaimer: This guide is for testing & educational purposes only. I’m not responsible for any loss of important data or malfunctioning of your iPhone.
Note for iPhone 3G and 3GS Users: We strongly suggest that you stay away from this official upgrade until and unless the DevTeam or George Hotz releases new jailbreaking and unlocking tools for 3.1.3 firmware. We will let you know when it will happen. In the meantime you can follow our complete jailbreaking and unlocking guide for iPhone 3.1.2 firmware using blackra1n, PwnageTool, redsn0w, sn0wbreeze, ultrasn0w and blacksn0w.
UPDATE 1: Sn0wbreeze 3.1.3 -V1.3 is LIVE! Follow the guide posted here to jailbreak iPhone 2G, 3G and iPhone 3GS (older bootrom only) on iPhone 3.1.3 firmware. iPhone 3G and 3GS can then be unlocked using ultrasn0w or blacksn0w. iPhone 2G can be unlocked using the guide posted here.
UPDATE 2: PwnageTool 3.1.5 for Mac OS X is now LIVE! Follow our complete step by step guide posted here to jailbreak and unlock iPhone 2G, 3G, 3GS and iPod touch 1G, 2G on iPhone OS 3.1.3.
UPDATE 3: Jailbreak iPhone OS 4 with Redsn0w 0.9.5 is here. Step by step instructions can be found here.