So I got my first ever iPhone and it's the iPhone 4. I have the 200mb plan and I plan to switch cellular data off most of the time if wifi is available to avoid overage. Thing is, with cellular data off, I can't do certain things (ex. Receive picture messages via the Messages app) unless I turn on cellular data. So as long as wifi is available, will my phone still use up cellular data even though it can get data off the wifi? Thanks. I apologize if I failed to look up any threads on a similar subject. I did a quck search but they weren't really what I was looking for.