1. iphonestar's Avatar

    I have a US AT&T unlocked Iphone 3GS running on ios 3.1.3 and baseband 05.12.01. I would like to upgrade to the latest ios5 to take advantage of the icloud functionality. I am currently running my phone on O2 network and I don't have the original AT&T sim. Is it possible to do this currently or do I need to wait for some time ? Also, I am a newbie and would greatly appreciate if you could give me detailed info on how to do this.

    Thanks for your help !
    01-15-2012 05:00 AM
  2. Tony the Tiger's Avatar
    You could use redsn0w to preserve the baseband to keep it unlockable and hacktivate it so you don't need an AT&T sim to activate it via iTunes.
    01-16-2012 02:12 AM
  3. iDonev's Avatar
    I recommend following this tutorial in order to upgrade to iOS 5.

    A couple of pointers:
    In Step 4 when you choose Expert Mode, go to General and tick the box called "Activate the iPhone"

    You have no need to install the 06.15.00 baseband.

    Speaking from experience it's a bit hard to tell when you should use iBooty during the firmware upgrade. After you see the a message on iTunes that the phone has been successfully restored, start iBooty and follow its instructions.

    After installing iOS 5 (after you complete the Welcome settings on the iPhone), fire up Cydia and install the following tweaks:
    Corona - this will untether your jailbreak, meaning you won't need to use iBooty any more.
    ultrasn0w - this will unlock the phone so it will work on O2
    SAM - this tweak will enable iMessage and push notifications. Get it by adding repo.bingner.com to your sources in Cydia and then follow this tutorial.

    Good luck
    Last edited by iDonev; 01-16-2012 at 01:42 PM.
    01-16-2012 01:39 PM