My deactivated iphone 4 still connects to 3G?

My iphone 4 is deactivated but it still connects to 3G and I can use internet and apps. Calling someone else doesn't work though. Is this normal? I thought only Wi-fi still works after deactivation.
If it continues to connect to 3G, will I get charged for it? So confused.

3G *is* Wi-Fi. And if you want to call someone, install SKYPE - and have your friend do that, too - and you can call them for free. If you want to call people who have landlines or are NOT on Skype, put a few bucks into your Skype account, and you can call them for 2.3 CENTS a minute. So you can use your deactivated phone for Wi-Fi, for a music player, and games - you just need to be using Wi-Fi or a hotspot or Skype will not work, so it is not Really a cell phone - just a *sometimes* phone when you get connected. Better than nothing - and you can collect your messages when you DO get to a hotspot.