iPhone Dev-team is only work on downgrade 6.15.00 baseband for iPhone 3GS and iPhone 3G only. Unfortunately there’s no method to downgrade 4.10.01 to 1.59.00 baseband, and iPhone Dev-team didn’t even promise to work on this scheme.

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 6.15.00 baseband.

Someone asked MuscleNerd on Twitter if there are any updates about downgrade 6.15.00 to fix GPS problem, MuslceNerd replied that he won’t release downgrade 6.15.00 baseband before iOS 5 public release which expected to be between the end of September to start of October.

Someone asking MuscleNerd : man any news about 06:15 downgrade, i need my nike+Gps

MuscleNerd replying: there’s a good reason not to release anything like a downgrade that before iOS5 (though sometimes I think I overthink it!)

So that, it’s highly expected that downgrade 6.15.00 baseband to fix GPS problem is almost completed, but as usual all hackers are holding their major hacks, jailbreaks and unlocks after iOS 5 release to keep them away from Apple hands.