You can pick them up for cash but often times they will ask to see your passport. They don't bust through the great firewall but in my experience foreign sims don't seem to either.
I've been traveling a lot and what I've done is setup an AT&T based MVNO on my iPhone's eSIM, freeing up the physical slot for local SIMs. With WiFi calling enabled on my AT&T line, I can go around the world spending peanuts compared even to Google Fi, while keeping my US number working.
T-Mobile US' international roaming was almost useless when I was in Japan before the pandemic. Coverage was good on SoftBank, but even with five bars, my latest-and-greatest T-Mobile 4GLTE hotspot would only connect as 3G, and the speed was closer to dialup.
It seemed more of a marketing gimmick than a useful tool.
I think the basic problem here is that there's essentially no overlap between the LTE bands used by T-Mobile in the US and Softbank in Japan.
Unless you have a device with radios that happen to support extra bands that are not used in the US, then it's essentially incompatible with the Japanese network despite both being "LTE".
I disagree, it's a great tool - T-Mobile has roaming agreements with Softbank, NTT and DoCoMo, not KDDI.
The biggest issue is the phone bands, if your phone does not support the local bands, it will not connect.
I had no issue having a secondary phone in Japan w/ my T-mobile sim and having a local NTT sim. With dual sim/esim even easier nowadays to run both networks.
It actually gives you 5G in Canada and Mexico for free, which is particularly useful to me.
In international locations to your point it gets you enough for Maps and Mail, and some basic web browsing. You won't be streaming, that's for sure. However, if I need more than that, I use it to bootstrap an e-sim like GigSky which you can then route all data traffic to (at least on iOS) via Cellular settings.
This way you keep your phone number, iMessage, texting, and get 5G data too.
I couldn't disagree more. Of course T-mobile's free roaming isn't going to be super fast. You can pay extra 4G/5G. But if you're hopping across countries, it's great. It's obviously not made for instagram/youtube.
T-Mobile's free 128kbs is enough for whatapp, navigation and a few emails (Their MAX plan gives free 256kbs).
I had terrible problems with T-Mobile US international roaming in Japan also. I was able to make calls and recieve calls, however I was not able to use internet.
After basic troubleshooting T-Mobile requested that I call their international support on a 2nd phone and they would happily help me fix the problem with the original mobile phone.
Of course I didn't have access to a 2nd phone, I was livid. Cancelled the contract with T-Mobile and got local service. Even in cancelling T-Mobile couldn't get it right, they sent me two additional bills for trivial amounts in the months that followed. Each bill under a dollar.
I'm no longer with T-Mobile US but I used it in Peru, Iceland, Mexico, Morocco, Brazil, Bolivia, and Italy without issue. Maybe Japan is a fluke but working service in North Africa and South America speaks volumes for me.
I don't rely on their international roaming to do hotspot work, but it suffices to check HN, use google maps to get around, and order uber if I am in a place w/o amazing mass transit.
