What still works with Data Roaming off?

If you aren't planning to purchase any type of international plan, here's two suggestions.

1) Put the phone in Airplane mode & turn on Wi-Fi when needed.
2) Remove the SIM card while you're away. This may not be the best idea since the SIM is needed if you have to restore the phone. If you do choose to remove the SIM, make sure you have it with you in a safe place.

~Lyssa

Data Roaming should prevent any data or internet access via a cellular network when roaming intetrnationally. This means any app that requires internet access to work will not work. To ensure you don't have any surprise charges, turn Cellular Data off as well when you don't want or need internet access via the cellular network.

The includes Maps app requires internet access for maps data to be downloaded for a particular location. There are a number of 3rd party GPS navigation apps with maps data included and stored locally on the iPhone with the app so internet access is not required to access maps data with the app. Although the iPhone uses A-GPS or assisted GPS, the iPhone includes a dedicated GPS receiver. The assisted part helps to speed up the initial location and GPS acquisition only from a cold start, but internet access via the cellular network is not required for GPS acquisition, but the initial GPS acquisition from a cold start will take longer with Data Roaming and Cellular Data turned off when roaming internationally.

Geo-tagging of photos does not require internet access, but without internet access the location tagged with a photo may not be as accurate.

Turning Data Roaming off and Cellular Data off does not prevent you from placing and receiving calls and the same for SMS. Calls and SMS are expensive when roaming internationally as well, but not as expensive as data or internet access via the cellular network when roaming internationally.

Airplane mode disables all iPhone radios - cellular for calls, SMS, and internet access via the cellular network, GPS, bluetooth, and wi-fi. After enabling Airplane mode, it is possible to enable wi-fi and/or bluetooth only with the rest of the radios remaining disabled.

A lot of things will still work, like your camera, your videos, photos, music and your navigation system if it's stored on your phone. I was in Italy last September and every hotel that I stayed at had Wi-Fi. In addition, for $60, I purchased 50MB of data, which, with all of my free Wi-Fi was more than adequate for the trip.

You're welcome.

If you turn Cellular Data and Data Roaming on when roaming internationally, if any app that requires internet access accesses the internet for any reason, you will be charged for data access at international roaming charges which is very expensive. If you turn Cellular Data and Data Roaming off, any email downloaded when doing so will cost you. If the geo-tagging of a photo uses assisted GPS, you will be charged for data access for the assisted part.