i have a carrier free iphone 3G. now on 3.0 software (7A341). Carrier: Carrier 4.0. i dun have the tethering option under setting> general> network. i tried help.benm.at config, it work. i able to see the tethering option available but once i plug my iphone onto my laptop & turn on the tethering the thethering service option gone. just dissapear like that.. can anyone help me on this?