Are you annoyed by the iTunes pop-up telling you to update to latest firmware as soon as you plug-in your iPhone into your PC? Currently running firmware 3.1.2 and want to use all those 3.1.3 only apps out there? Or do you know someone who may accidentally upgrade their iPhone 3G or 3GS to the stock 3.1.3 firmware and lose their jailbreak and unlock? BigBoss’ tweak ‘Firmware 3.1.3’ is just for you!
Released in Cydia, what this tweak does is fooling your iPhone and iTunes into believing that you are actually running OS 3.1.3, whereas the real firmware version is 3.1.2. This is possible because the two firmware are really similar; after all, Apple pushed the latest one only to counter the jailbreak community before its major 4.0 release. Also, since the APIs for both firmware don’t really have any changes, 3.1.3 only apps would also work. iTunes, too, will stop bugging you for an update because it will believe you already are running the latest 3.1.3 firmware.
What this hack actually is doing is updating the file at /System/Library/CoreServices/SystemVersion.plist, which contains firmware version information. Due to the similarity of 3.1.2 and 3.1.3, this hack is exclusive for iPhone OS 3.1.2.
Firmware 3.1.3 is available as a free download in Cydia via BigBoss repo.
Update: BigBoss has removed the Firmware 3.1.3 Spoof from Cydia and replaced it with a spoofer app that can be used to toggle between reported firmware 3.1.2 and 3.1.3. The move comes due to some bug in the uninstall feature of the old Cydia spoof. Please note that if you had already installed the spoof, do NOT remove it. Install the new app over it. Removing it can cause your plist file to get removed, making your device useless. Read more here.