I’ve been using their 15$ unlimited plan here North of the border for about 2 month now..
Their in vehicle WiFi actually covers the entire North America, not just US..
So long as you were able to manage the payment process, they only take US credit cards.
However I was able to get around this by calling ATT customer service and ask them to manually charge my Canadian Credit Card.. eventually worked after trying several credit cards.
Hope this helps.
I wonder, what are prices in Canada now, in the 2020. It's completely insane, though. Even if it has become twice cheaper since then. I wonder why. Maybe there is something wrong with internet providers in Canada? I don't understand. My brother works as a network engineer in the USA. He passed exams using New Cisco Certification help just 2 months ago. And he says that in the USA it's much cheaper. Maybe it's because of Canadian climate? I dunno. Someone explain it to me.