For now we have been talking about jailbreaking and unlocking iPhone OS 3.1.3 through software which is mainly a Jailbreaking tool and then an app from Cydia to unlock the jailbroken iPhone. But now it seems that ElektroPower from Turkey have managed to flash the iPhone OS 3.1.3 baseband and re-flash it with the older baseband 04.26.08 which can be easily unlocked.

Download iOS/iPhone firmware for iPhone (2G, 3G, 3Gs and 4), iPod Touch (2G and 3G) and iPad

Important

Now you can do untethered Jailbreak of your iPhone 3G/3Gs running latest firmware 3.1.3 with "Spirit".

Step by Step iPhone 2G/3G/3Gs Firmware 3.1.3 Jailbreak Guide Using Spirit

Here’s the video that shows how the guy reflashed the older baseband.

Note:

Playing with the iPhone hardware will permanently nullify it’s warranty. This video is posted here for informational purposes only and ProgrammerFish will not be liable to any damage you may incur.

Unlock and Jailbreak iPhone 2G, 3G and 3Gs: