people in the rick steves link say you just tell tmo when you get back in the us to reset it/turn it on for the us. This should not have unclear limits of course.
The issue with having an explicit threshold is super heavy users will use right up to the limit and recommend it to other super heavy users. This MVNO then gets a disproportionate percentage of unprofitable roaming costs. The solution is for them to pass through the costs so there’s no dancing around the costs by suddenly cutting you off.
