Like the name implies, it’s a special online connectivity setting that lets you “roam” and use your mobile phone plan’s gigabyte allotment for internet use. However, unlike regular cellular data, data roaming specifically refers to the ability of your iPhone to connect to the internet over a cellular data network not covered by your phone service provider. Simply put, it pertains to using wireless connectivity while you’re in a foreign country that’s not included in your phone carrier’s coverage areas.
Apart from the basic service offerings, most unlimited U.S. phone plans offered by major carriers like AT&T, T-Mobile, and Verizon also offer unlimited talk, text, and data in Canada and Mexico. If you’re planning to head elsewhere abroad, you may need to get in touch with your phone carrier to find out what your international plan add-on options are. Depending on your iPhone model, carrier, and region you’re traveling to, you may have certain cellular data options available to you, so it’s important to reach out to customer support so you can get advice on how to configure your mobile device’s data roaming-related settings.