need some help! install itunes without sim card

hello there, i`ve bought the Iphone 3GS 16gb, from england sealed, from a guy, he told me it runs on vodafone, the problem is i`m back in romania new, but i havent download the itunes yet, because i don`t have the vodafone uk sim card, and i tried with a romanian vodafone sim card but when i try to install the itunes it keeps telling me: The SIM card inserted in this iphone does not appear to be supported. why??? isnt the same network ??? how can i install the aplication without an an UK Vodafone sim card... ??