What are the iPhone restrictions for travelling abroad?

Hi:-)
I'm travelling to Italy tomorrow for a week. I have an iPhone 4S.
I'm looking for a detailed explanation of dos/don'ts with my phone throughout the entire journey - particularly regarding the Internet.
Include:
- Travelling on a plane to Italy.
- What to do with it once I get to Italy.
- What to do during my trip.
- Travelling home.
More info the better, and the main focus of this is No Surprises On Phone Bill!

Hoping your phone is unlocked, once you get there, buy a local SIM for your usage and/or run off Wi-Fi (get the vonage app so you can call back to the US for free). You'll get iMessage for free with a wi-fi connection, but I'd avoid text otherwise. You can't use the phone on the plane, unless they offer wi-fi access, (or go into airplane mode, check with your flight crew so you don't get into trouble) Make sure you have an international power plug that will work there, the AC plugs are different.

Check out the iPhone website.

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