How to restore iOS 5.1.1 custom IPSW using iTunes without errors

Users relying on software carrier unlock ultrasn0w must use sn0wbreeze created custom IPSW firmware to upgrade there iDevice to an upgraded iOS version without updating the baseband which breaks the unlock. However, Apple iTunes prevents users from upgrading or restoring to these custom IPSW files and errors out the process with codes 3194 and 1600 - for which we have shared solution earlier. Here is an step-by-step guide to restore an custom IPSW file to iPhone using iTunes the correct way without any errors.

Correct method to restore custom iOS 5.1.1 firmware using iTunes :

1. Make sure you have saved your SHSH blobs using TinyUmbrella.
2. Using these saved SHSH blobs, create an custom signed IPSW file using sn0wbreeze.
3. Put your device into Pwned DFU Mode.
4. Now, launch iTunes and it should detect your iPhone in recovery mode.

5. Makes sure TinyUmbrella TSS server is running.
6. Shift + Click the Restore button in iTunes and browse for the signed IPSW file created in Step 2 above.

7. Confirm the restore.

8. Let the process complete.

9. Your iPhone should now have the jailbroken iOS 5.1.1 with ultrasn0w supported lower baseband version.

10. Proceed with installation of hacks like ultrasn0w using Cydia.