1. The first tip is about the battery issue. The team mentioned unusual battery depletion is almost always caused by choosing “Restore from backup” instead of “Setup as new iPhone” when iTunes prompts you during the initial setup. The battery depletion issue is no related to jailbreak or ultrasn0w tool but it’s common for iPhone 3.0 if you’re using “Restore from backup” option to restore back your iPhone. And, here is the possible fix:
The fix is to just re-run the official 3.0 restore and choose “Setup as new” this time. Your music and apps and all that will still be synced, but you’ll get rid of any conflicting wifi, bluetooth, or carrier settings. Then just re-run redsn0w and install ultrasn0w.
Personally, I used “Restore from backup” option to restore back the iPhone. Not all jailbroken iPhones experienced this battery depletion issue. But I did turn off push notification and push email to preserve battery. But if you encounter this issue, I suggest you to follow iPhone Dev team’s recommendation and re-jailbreak your iPhone again.
2. For T-mobile USA user, remember to turn off 3G before using ultrasn0w. Ultrasn0w does not support 3G service of T-mobile USA (actually, it’s not ultrasn0w’s problem but due to t-mobile’s non-standard 3G).
3. Remember ultrasn0w only works on hacktivated iPhone. That means, even you’re using the official carrier, please don’t use the official sim to activate the iPhone via iTunes. Use redsn0w for the activation (i.e hacktivate) and keep your unofficial sim card in iPhone all time when using ultrasn0w.
4. For certain unofficial plans, they have limitations on whether you can make calls and use data at the same time. That’s not unlock-related.
For those of you experience any unlock problem while using ultrasn0w, remember to read through the above tips and go through the jailbreak & unlock process again. For details of the tips, you can further check out iPhone Dev Team’s post. If you’re planning for jailbreak and unlock your iPhone 3G/3GS, you can also check out this step-by-step guide for iPhone 3G / iPhone 3GS.