The 9300 works on the mini-SIM. You can use any SIM card that will fit without wrecking your unit. You could use the micro-sim with an adapter, but probably not the nano-sim as the contacts would not line up.
ok I did not know what the black berry can use or not all I know is I am use to analog digital and and the Blackberry 9300 takes sim card . I have the small card for my Iphone 4S i dont have the large one I was told to get it " a store so i can use with my provider.