I too was wondering this, I'm going on a cruise in a few weeks and wanted to know what settings to use so that I won't rack up obscene charges. I just want to bring my iphone 4 and use it as a camera/video recorder.
So..
1. Make sure roaming is turned off
2. Make sure airplane mode is turned on.
Is that it?
If you're going on Carnival their WiFi service is expensive and slow. Not worth the money at all.You can skip step 1. Airplane mode physically turns the radios off. There's no way to roam if the radio has no power.
Also, add to that a final step: "Turn Wifi Back On." This will leave airplane mode on, but with Wifi. You can use any free Wifi signals you find and Airplane mode will keep the other radios off.
I'll be traveling to Jamaica in one week and re hashing this subject back....all I need to do is flip airplane mode on and then flip wifi on when I get to the hotel if they have it and I should be all set, right?
Airplane mode kills WiFi too.
Turn off Cellular Data and Voice Roaming and you should be good.
BTW I just spent 2 weeks in Jamaica, their network is CDMA. Roaming there from Verizon is $0.50 per outgoing text, $0.05 incoming texts (I think), and $0.99 per minute voice. Data is insane, $20.00 per MB!!!! Both resorts I went to had WiFi.
If you're going on Carnival their WiFi service is expensive and slow. Not worth the money at all.