I have no confusion about that. I'm speaking of T-Mobile's policy on tethering, and their equipment
problems with tethering, for US customers. Those policies and problems will very probably persist, regardless of whether the customer remains in the US or travels to other places. If there are further restrictions on tethering when abroad, T-Mobile, as usual, doesn't tell anyone about them.
A friend of mine, also a US TMob customer, recently went to Brazil
and before he went, he confirmed that he could make free voice calls there, paying only for data if he used it. He went over how to disable data with the service
rep. And after he got to Brazil
...found that he was still being billed for data services because of the way they were forwarding text messages--without his knowledge and despite their statement that the services he was using would be free.
Where you use the phone
, is almost irrelevant compared to where your service
is based, because that's the over riding factor in how the plan will be governed. Even in the rare event that the rep knows more than what they see in a binder.