Hey there! Sorry to read that we missed the chance to welcome you to Hong Kong! I did a double check here and it looks like you should be able to roam there -- International Plans | Traveling Abroad without Roaming Fees | T-Mobile. I know it's been a few days -- did you receive a delayed message? How are things going, were you able to connect?
Side note: it looks like your original username was set as a phone number. I went ahead and proactively changed it for your privacy. If there's another username you'd prefer, please take a look in your inbox and reply to the message I sent to you! Thanks, and welcome!
We know the text you get when arriving in a different country is helpful. As Marissa mentioned, you should be able to roam in Hong Kong and she provided info on our International plans so you can see your rates and coverage. Please let us know if you have any other questions after looking over the link Marissa replied with a few days ago.