For all owners of locked devices, we offer direct links for downloading ready-made custom firmware without upgrading the modem, created using Sn0wbreeze v2.8b11 (For iOS 5.0 / 5.0.1). With these firmwares, you can further unlock your iPhone 3GS or iPhone 4 using Ultrasn0w or Givey Turbo Sim or untethered jailbreak iOS 5.0.1 using Redsn0w 0.9.10b1.
1. Download and run the Redsn0w 0.9.10b1 program.
2. Connect your device to your computer.
3. Press the Extras button.
4. Select Pwned DFU.
5. Follow the instructions on the screen to enter the device into Pwned DFU mode (read also how to enter the device into DFU mode here).
6. When finished, click the Done button. The device screen should be black.
7. Open iTunes. It will detect the device in DFU mode and offer to restore.
8. Press SHIFT on your keyboard and left-click on the Restore to iTunes button.
9. Select the desired custom firmware (you can download it here) and click Open. After that, the recovery process will go.