If you are traveling with your iPhone 6 in foreign counties, then you should keep the topic of "data roaming" in mind. Data roaming abroad can be quite expensive, especially in countries like Europe, India or China where prices are charged up to 12 $ per megabyte and with no cost airbag. Therefore, please check on your iPhone 6 that the following setting is disabled before doing a trip to a foreign country. You can do this in iOS as follows:
Open on the iPhone 6 the settings and then select "Network". In this menu you can now find the "Data Roaming" option. The switch must be set here to the"Off" position. This is the only way to ensure that no mobile data will be used by your iPhone 6 abroad.
You now know how to check on the iPhone 6, whether Data Roaming is disabled, and how you can turn off the Data Roaming.