So I tried my hotspot@home phone in Germany and it does work once you are connected to a wifi network. It does NOT work with T-mobile hotspots in Germany though as it doesn't automatically connect like it does in the US. Even if you sign up to the hotspot using your laptop, you cannot enter the MAC address of your phone, and the phone cannot view the signup page to enter user/pass.

In summary you can get it to work at home near your wifi router, or any AP that is open or you know the security key. It does not work with hotspots overseas that have a signup page, even if they are T-mobile.