Help with Upgrading to 4.0 for a used jailbroken iphone
I am a new member here. I've a very interesting question:
I just bought a used iphone running jailbroken 3.1.2. So, that means I don't have original owner's sim card.
However, I have my own AT&T sim card (without data plan). I would like to upgrade this phone to a normal (not jailbroken) firmware 4.0. I don't care about losing applications or data that came on this used iphone. My questions are:
1) What are the steps to upgrade my iphone to official 4.0 ?
2) Do I need to first restore it to factory settings ? If yes, how can I restore this used jailbroken iphone (running 3.1.2) to unjailbroken factory setting without original owner's sim card ?
3) After restoring, do I need to get data plan (which I don't want to buy) to use it with my sim card ?
Thanks for your help in advance.