Does T-Mobile charge my Android Optimus 2X extra if you use WiFi?

[kells_pn]

I have an Android Optimus 2x form T-Mobile but I have no data plan so I can't do anything on my phone that requires internet (Facebook, Twitter, Browser, GPS, etc). If I connected WiFi onto my phone and went on Facebook or Browser, would they charge my phone even though I'm not using 3G?

 

[Winston]

Once connected to WiFi, you are no longer using 3G so you won't get charged.

I don't have a data plan either but I've completely disabled any data connection via 3G. It only goes on the internet when I connect it to a WiFi network.

You should disable 3G data connections as well if you don't have it (saves batteries too). This can be found in Settings.