Recycle iPhone4 - Erase all data.
As I now have in iPhone4S, I wish to recycle my 'old' iPhone4. My service provider, O2, have a recycle facility where they will BUY my phone back for it to be recycled.
I have decided to use this and get a bit of money back from my unused phone.
Before I send it to them I obviously want to delete all my personal data so it cannot be retrieved. Is selecting the 'Erase data and reset settings' option from within the Settings menu on the iPhone good enough, or is there a better, more secure way?