On Prada 2 phone, is connecting to wifi free or do you have to have a data plan?

I'm looking at getting a new phone. I am very impressed with the Prada 2 phone and saw that it has wifi...in order to use the wifi, do you have to purchase a data plan? And I have at%26amp;t so would it work with that network? Also, I'm interested in the samsung impression but it does not have wifi. If anyone has either phone, could you please leave some opinions. Thanks!|||Using wifi is free. An unlocked Prada will work on the AT%26amp;T network but AT%26amp;T will require you to have a data plan. AT%26amp;T requires a data plan for all smart phones.|||Using WiFi is free. With WiFi you connect to a previously set up wireless network. It's the same thing as a wireless connection with a laptop. If you use AT%26amp;T's internet service on the phone however, then you will get charged if you don't have any sort of data plan.