If you previously unlocked your iPhone 3G or 3GS, chances are you are on the 6.15.00 baseband. This baseband is also known as the iPad baseband and many users have reported inconsistent GPS signal. Follow the step-by-step video below to get your baseband downgraded to a more stable, unlockable, version. In this video, we will be downgrading our 6.15.00 baseband to the more desired 5.13.04 baseband. As always, the download links are below for your convenience.