How can i avoid the extra charge with at&t smartphones?

Right now i have an lg incite (smartphone) that i bought with a contract before the new data package policy with smartphones. My dad block internet on our plan so even if i wanted to go online i can't. I recently bought a Samsung blackjack 2 from ebay and wanted to know if i put my sim in the new phone could they detect it's a smartphone and add the data package to my plan even though i have internet blocked? If they can could i do anything to avoid it? The only thing i use my phone for is talking and texting so i would have no use for the the whole data package.