cellphone data plan on a smart phone

OK i know this is my first post but I've read probably as much as you guys so don't bash, OK here's what I've found, my first phone was a Sony ericsson w580 just  regular feature phone i had no internet and only text messaging then i upgraded to a blackberry 8800 and didn't change my plan to a higher message plan like your supposed to with att and when i called them the lady told me that in their network the messaging was still set for the w580 even though i was using a BB.

now that being said now i have my impression and im paying 30 dollars a month for unlimited data and text, i also have a Motorola q9h and since the impression been giving me problems with the text bug and all that i was thinking that i can probably switch phones and still be able to use the internet and text on the smart phone, so i switch my phones and GUESS WHAT!!!! the internet worked, i went on you tube and received text.

so i want any body that have a smart phone to try this and give me feed back to see if it works for everybody. hopefully this is like i think it is.

so goat if i get a tmobile unlocked phone i might be able to get away with it? i just want a smartphone but dont want to pay the like 50 bucks for everything and the impression is going to get fun when you guys find the firmware.

goat and are you currently using a smart phone and if you are, do you have the cellphone data plan or the smart phone?. and thanks for all the info so far.

jajaja then i think im going to go for a smart phone and see what happens and again thanks