Need to clear personal info from unlocked iphone 3g dont know how to unlock again

[flwerchild]

Hi everyone,

I'm really hoping that some of you guys will be able to help me. I had originally bought my iPhone 3G unlocked from ebay brand new a few years ago. I recently sold it on ebay as a used unlocked iPhone 3G. My problem is I would like to know how to go about clearing all my personal info off of the phone before sendig to the new owner. I have read enough to know that doing this will cause the phone to lock again.
So, I don't know how I would go about unlocking the phone again being that it had already come that way for me. It is running on a broadband of 2.30.03 and I've heard conflicting things about unlocking the phone again on that bb. Yet, I have never updated the software through itunes. The phone has always been on that bb. There is some kind of sim card that has always been under my t-mobile sim. I don't know if that makes a difference at all.
I wasn't planning on having to do all of this to sell so any help would be great at this point since I don't know how to go about unlocking again!!

 

[PsstGreek]

Wow you're running a pretty old baseband. Upgrade the iPhone to 3.1.2 in iTunes. Download Redsn0w 0.9.2 to jailbreak and unlock with ultrasn0w. Restoring/upgrading will remove all your data.

Here's a guide on how to do to so: http://iclarified.com/entry/index.php?enid=7443

 

[aristobrat]

If all you want to do is clear your info, can't you just use Settings > Reset > Erase All Content and Settings?

I think it takes awhile on the 3G, but it should get the job done.