Expert: DebiN - 12/28/2009

Question
I have a jailbroken/unlocked iPhone (I used blackra1n to jb/unlock it if that matters)
I want to restore my iPhone to fully factory AT&T settings and relock it. I've read if I use someones sim who has AT&T, insert it to my iPhone then restore it, it will compleatly lock it back up, run a new certificate to the iPhone and the iPhone will be as it was when I got new out of the box. Is this also true if I used a AT&T Go Phone sim?  
Will these same steeps work if I were to try to restore and it using a go phone sim?  (I'm trying to lock it back up so I can get it back to factory settings so that I can have iTunes reset all my settings back to factory, then reunlock it. My push and YouTube are not working and I don't want to download Cydia. It's what got me in this mess in the 1st place. )  

Answer
A locked iPhone can't read a GoPhone SIM card (it's just like if you were using a T-Mobile SIM card or other non-AT&T SIM card), so using the GoPhone SIM will not allow you to do what you are wanting to do.

You should be able to get the iPhone back to it's original settings without a SIM card in it at all. All you have to do is to remove the SIM, tether it to your computer and iTunes and then tell it to restore it to factory settings. If this doesn't work, it may be because of the way it was jailbroken and if that is the case, I'm not aware of another way to do this and don't believe that putting an active AT&T SIM card will solve the problem. I hope this helps. Thanks. DebiN