Help with Upgrading to 4.0 for a used jailbroken iphone

[sbtechie]

Hello all,

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.

 

[OTACORB]

All you need to do is install iTunes 9.2, then plug it into your computer. It will tell you there is an upgrade. Click you don't wish to upgrade. Then click on restore. This will totally restore the phone with iOS4 just like it has come out of the box with it. Then when it restarts it will ask you if you want to set it up as a new iPhone or if you have any existing back-ups to use one of them. You want to set it up as a new iPhone. You'll be all set. I'd say go ahead and put your sim in there prior to doing this.

If you have an iPhone on AT&T network you are REQUIRED to have a data plan. You can do the 200mb one for $15. Just make sure you don't go over and in fact you can actually turn the data off in settings to make sure.