Starting October 20st for new accounts (and October 31st for existing accounts), T-Mobile is offering nearly unlimited international data roaming for its US customers. I remember the days of roaming within the US where you would pay roaming charges for phone calls outside your home network area (which, back then, were narrowly drawn). Those were the days when banking and many other services were not truly nationalized within the US. Interstate commerce had its internal borders.
That eventually gave way to unlimited nationwide roaming and the now commoditized domestic mobile phone and data service. Most other inter-state barriers have now fallen. T-Mobile's move to remove international data roaming across its broad network is groundbreaking and will, in due course, serve as an international leveler. It's high time. Kudos, T-Mobile!