GSM-Forum - Download Custom Firmware 3.1.2 ipsw – Jailbreak, Activate, Unlock iPhone 2G, 3G, 3GS

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iPhone 2G, 3G, 3GS users can now safely update to 3.1.2 firmware without updating the baseband (for unlock). If you are not the one to download all the various files and just want the ultimate result, these files are waiting for you to download! If you rather want to start from scratch, download

Caution #1 : A restore is going to wipe the iPhone clean. Hence, please backup your iPhone using iTunes and then proceed.

More info about these custom firmware files :

Has factory boot logos (Apple and restore cable),
Only Cydia, No Icy
Preserved Unlock baseband (that is the whole point of a custom firmware, right?!)
Activated/Not Activated (Check the files carefully)

Prerequisite (recommended) :
If your iPhone is already jailbroken at the current firmware (3.0, 3.0.1, 3.1), it will be a hassle free upgrade! Restore mode will work just fine with already jailbroken iPhones.

Step 1.1) Download Files for iPhone 3GS (Please read the following carefully)

3gsiPhone 3GS 3.1.2 Custom Firmware Activated for Other Carriers Part 1
iPhone 3GS 3.1.2 Custom Firmware Activated for Other Carriers Part 2

iPhone 3G 3.1.2 Custom Firmware Activated for Other Carriers Part 1
iPhone 3G 3.1.2 Custom Firmware Activated for Other Carriers Part 2

iPhone 2G 3.1.2 Custom Firmware Activated for Other Carriers Part 1
iPhone 2G 3.1.2 Custom Firmware Activated for Other Carriers Part 2

Step 2) Join the downloaded files

The files downloaded above have an extension .001 and .002. They need a special opensource (free) software HJSplit to join.
Download HJSplit to join both the files – Link for Windows Computers here and Macs here.

You should now have the respective firmware file with an extension .ipsw (make sure it is .ipsw or else, it will give you an invalid firmware error) . Follow the steps in order :
1)Launch iTunes and connect the iPhone to your Mac / Windows computer.
2)If your iPhone is already jailbroken (if you see Cydia on your iPhone!), put your device in Restore mode (Turn iPhone off, keep holding Home button while you plug it in to your computer). Proceed to step 7. If not jailbroken already, continue to the next step (3).
3)If you are aware of DFU mode, proceed further. If not, watch this quick video and pay close attention to the steps to achieve DFU mode.
4)Turn your iPhone off. Press and hold the Home button and the Power button at the same time for 10 seconds.
5)After exactly 10 seconds release the Power button. Continue holding the Home button until iTunes pops up a message saying that it has detected an iPhone in recovery mode.
6)The iPhone will show you a blank screen (black).
7)Click on ‘Ok’ to the prompt displayed.
8)For a Mac : Hold Option key and then hit Restore button.
9)For Windows : Hold the shift key and then hit the restore button.
10)In the dialog box that pops up, browse the downloaded custom firmware file (the .ipsw file that you downloaded and joined using hjsplit in step 1.x).

Step 4) Give it few minutes to perform the restore. Once the iPhone is up and running, proceed for software Unlock using Cydia. Follow this guide to install Ultrasn0w to software unlock your iPhone 3G/3GS. iPhone 2G is already unlocked with this custom firmware!