Updated old 3GS phone, no sim card, want to make sure all data is gone

[sadcaper]

So I upgraded to the iPhone 4S and was preparing to sell my old 3GS. I thought I'd go ahead and upgrade to iOS5 for the new owner, so I did that.

However, I want to make sure all data on the iPhone is GONE before I sell it. I was planning to update to the new iOS, and then do an erase on the phone. Since the SIM is out of the phone now, I can't get by the activate screen on the phone.

Does that mean the phone is already wiped of all data and I can go ahead and sell it? Or do I need to somehow downgrade to 4.3 and then do a wipe first?

Thanks!

 

[AIP5]

When installing iOS 5, if you didn't restore from an old backup, then you should have a "clean" iPhone without any of your personal data, I think.

If you did restore from a backup, or if you have suspicions of restoring from an old backup, then just connect it with your iTunes and just hit Restore again. Be careful this time to not restore from an old backup, and to set up the device as a new device.

My understanding is that this deletes all your data on the device. I'm actually doing the same thing (selling my 3GS for the 4S).