Most of iPhone 3G and iPhone 3GS users updated their baseband to iPad’s one which is 06.15.00 to be able to unlock it. It’s not possible to restore using stock firmware on iPad’s baseband so you can downgrade to baseband 05.13.xx which is unlockable using ultrasn0w and you’ll be able also to restore using stock firmware on this baseband.
After MuscleNerd has declared about the new amazing Redsn0w jailbreak features, he has been asked about the downgrade for 6.15.00 baseband on iPhone 3GS and 3G after using ultrasn0w, he points that the work on the downgrade issue won’t start only after the release of iPhone 4 baseband 2.10.04 unlock which expected to see the light in less than a month.
Here’s a bit of good news for who suffered from the new unlockable baseband 6.15.00 on iPhone 3GS and 3G. Most of the unlockers who unlocked their devices with ultrasn0w 1.2 can’t restore to any stock firmware above 4.1, it only can be restored to a custom firmware, moreover, ultrasn0w 1.2 caused a loss of GPS. Let’s check out the new progress regarding downgrade 06.15.00 baseband.