You can unlock iPhone 05.14.02 baseband after the release of ultrasn0w 1.2 unlock for iOS 4.2
This unlocks iPhone with baseband 05.14.02 perfectly but the procedure is a bit different with a different procedure which is bit tricky.
To unlock iPhone 3G or 3Gs with baseband 05.14.02 on iOS 4.2 we need to update the iPhone to iOS 3.2.2. for iPad with baseband 06.15.00 first.
Click here to upgrade your iPhone baseband to 06.15.00 with PwnageTool or to upgrade iPhone baseband to 06.15.00 using redsn0w.
Once the firmware with baseband 05.14.02 has been upgraded to 06.15.00 baseband, you can unlock it by following the instructions at:
Unlock iPhone 3G, 3GS Baseband 05.14.02, 05.15.04, 06.15.00 with Ultrasn0w 1.2.
This will let you successfully unlock iPhone 05.14.02 baseband with iOS 4.2.1