tethering on jailbroken iphone?

[Michael]

Hi guys, i have recently got an iphone which i jailbroke.I enabled internet tethering on it and thought all was well. To my shock i got my phone bill through and some how vodafone knew I'd been using it for internet tethering. AM i missing something here? I thought if u enabled internet tethering on a jailbroken phone it would be free. I;ve been on help.benm.at and there are know vodafone profiles there. Any help on what ive done wrong would be greatly appreciated. many thanks