The last thing anyone wants to receive after a nice relaxing overseas vacation is a huge cell phone bill because of data overages.
These days nearly every smart phone uses background data to keep information on your device up to date.
This is fine when you are connected to your stateside smartphone plan that usually has enough of a data cap to allow that background data download and your normal ussage.
However, when you travel overseas things change very quickly. Some companies offer very little by default for your current cell phone plan when it comes to overseas calls and text messaging let alone data.
Now most of those same cell phone companies do offer short term options to cover you with a plan that reduces the cost of using your smartphone overseas and many, such as the one I typically use, gives me unlimited text messages, up to 120MB of data and 50% off phone calls (still .50 cents per minute though).
It is easy to keep yourself from making calls on your phone but controlling background data on a smartphone, in this case a Windows 10 Mobile device, presents a bigger challenge in closing the background data flow.
This gallery will show you the key spots in Windows 10 Mobile to make sure data is turned off so that you can maintain total control over that background data.
If you want to verify your settings, I recommend using your carriers website and looking at your real-time (or almost real time) data reports for 100% verification that no data is leaking across your phone while roaming.