Not sure of the answer to this but your best option is to contact VZW directly to get an answer.
Is this a CDMA or GSM iPhone that you have? Assuming it's GSM, I can only think of T-Mobile (limited to 2G data speeds), Simple Mobile (limited to 2G data speeds), H2O Wireless and TracFone/Net 10 as your options. The last three companies only have full-sized SIM cards, as far as I know, and you would have to cut it to fit your iPhone. AT&T doesn't support iPhones on pre-paid plans.