They're actively blocking North American and international iPhones from connecting to their Network. Apple has updates for each region that automatically download when you get there, but they're claiming it's a trade secret so only the phones they sell can get that update that's made by Apple for them. It isn't even a firmware update it's a little app that downloads in the background. Google does the same thing with Android, the pixel line, and anything running the stock with Google services or pixel experience.