Ok difficult question. I have an american iPhone 3g 2.2 Jailbroken and unlocked. I used it with the T-Mobile. I moved to UK now and i have an o2 dim. It works perfectly but i would like to upgrade my iPhone. What can i do?
Restore to factory settings and update to 3.0.1. Then jailbreak with redsn0w and unlock with ultrasn0w.
You can back up you apps first with Chronus and PkgBackup, but that's not a requirement, it just saves you some time setting it back up.
1- Back up your app store and stock apps with Chronus
2- Back up your jailbroken apps with PkgBackup
3- Back up your contacts with Google or Yahoo if you don't have Mobile Me
4- Sync your phone in iTunes,
5- Update to 3.0.1 and restore to factory settings (not from a backup)
6- Jailbreak with redsn0w using the 3.0 IPSW (you will remain on 3.0.1)
7- Unlock with ultrasn0w
8- Restore your jailbroken apps with PkgBackup
9- Restore your stock and App store app settings with Chronus