So a friend of mine (yes, a friend ) had this unlocked iPhone 3GS. I knew nothing about the unlock or what sort of unlock it was, and neither did she. She hadn't upgraded it for a long time and was on 3.1.2. I offered her an upgrade and she upgraded (the latest upgrade available today), but her SIM card stopped being recognized by the phone after that. I jailbroke it with limera1n and tried installing ultrasn0w, but it says in the middle of the installation every time I try it that it "Could Not Activate Cellular Data Network". After this failed installation, the SIM card went from not being recognized at all to being recognized, but just searching for a phone provider without finding one. I tried installing a custom APN for the Swedish phone provider, didn't help. I tried to use Pwnage tool, but apparently that requires a Mac OS, which I don't have. Any tips for fixing this? I'm willing to downgrade or do whatever it takes as long as it starts working again. Thanks in advance.