I’m on T-Mobile too. I’ve been international for 8+ months and haven’t gotten a warning yet. Interesting to know that you (woahitsraj) finally did: I’ve been wondering when it’s gong to happen to me. Based on your experience, it seems I have some time.
Regardless, I’ve decided that as great as the T-Mobile plan is, I’m actually tired of only 3G data and no ability to tether. I started looking at Fi myself. It’s complicated for me because I have (and want to keep using) iPhone, yet I know it’s still technically possible (after jumping through hoops).
I biggest issue is the fact that Fi has the same type of usage restrictions as T-Mobile, per Fi’s TOS: I can’t seem to post a URL right now, see attachment). Fi is related to T-Mobile only during usage in the US. Fi’s restriction isn’t related to T-Mobile. It’s just probably the case (as one would expect) that Fi’s contracts with the US carriers is considerably more profitable than the ones they have with other countries’ carriers. (I thought Google is a global company… sigh). I’m actually planning to call Fi’s customer support to find out whether or not they truly enforce their policy.
Aside from that, I’ve been looking at a number of other international SIMs. The best option I’ve come across thus far is: KnowRoarming. Not too great on price, but better than all others I’ve researched. And it’s a truly international solution, including the US.
I’m quite curious to know what others are doing.