I'm with o2 and have the Iphone 16gb 3G - 3.1.2 software and v5 carrier profile. I've got tethering enabled on the account - the 3gb is free as part of a deal that I've got on the contract so it's all legal and above board with the phone still being on official software - not jailbroken. However, the tethering option is never displayed in General>Network>Settings despite many attempts at resetting carrier profiles, resetting the phone and even doing a clean install. o2 are stumped and Apple refuses to touch it as it's outside of the 12 months yet is still in the 18 month contract. Any ideas? It's starting to get annoying that even though I'm getting official tethering, it just doesn't work. All other similar posts seem to relate to the carrier settings for avoiding the tethering charges and not a genuine tetherer not being able to tether!