Huh. I'm not sure then. United States is not even an option in the country dropdown for me but everything works if I enter a T-Mobile number, select T-Mobile. I had to comment out the country selection to get the test to move forward. In other words, it was not necessary for me to change countries. Maybe for the initial wifi test it can just be a phone number + carrier combo? Do you have to select a country to advance it in the UK?