I will get my iPhone on saturday from a friend whos gonna bring it back from new york.. Currently i have a blackberry 8800 on O2 with the blackberry unlimited tariff on it.. My question is: when i get the iPhone, will i keep the blackberry unlimited tariff and it's gonna work the same way as the iPhone was the blackberry or I will need to change my tariff?

(my O2 account is 35 a month with incl. minutes and txts + (on top) a 10 unlimited blackberry tariff.

Thanks a lot for you help!!