I was trying to find a way to use internet tethering again on my non jailbroken iPhones when I thought something simple.What is preventing me to use iPhone tethering function? My carrier’s new settings that iTunes suggests me to update on my iPhone. So I restored my iPhone and set it up from scratch, without using iTunes backup. Now when iTunes asks me if I want to perform this update, I simply click «no» and voila… iPhone with tethering without the need to jailbreak it.
This was tested at iPhone 3Gs and iPhone 4. Did not have the chance to test it at iPhone 3G but I think it should work.
UPDATE for Vodafone users:
Replace web.session with internet.vodafone.gr at tethering settings.