Hello everyone! I have a question and I hope you can help me. I have an iPhone 3GS, 4.2.1, 05.15.04 and I want to unlock it. I am planning to backup all my files with iTunes, then jailbreak it and the unlock it with RedSn0w. I understand that this will change my broadband to 06.15 and the risks. My question is: If something goes wrong with the Jailbreak and I need to reinstall the stock firmware using the iTunes backup, will I be able to bring back my iPhone to the same state before jailbreak (including broadband 05.15)? I have read that after installing RedSn0w the GPS might now work properly. Thanks a lot for your help!