When I cross the border into Canada, I get at least a couple of text messages that tell me that I can continue to use my phone, and will be using "Shaw Network", I think it is. I don't use my cell phone in Canada, but would if it was an emergency, of course. I have been wondering if I get charged, and probably should just turn it off before I cross the border. Yet, it's not which side you are on, but which side the cell tower is.
If you like having fun with the phoney "Windows Technician" calls, ask them what you need to do to fix the damned thing. They'll tell you to push a couple of butons...I don't recall which. DON'T! But tell them you did. They'll ask what you see on the screen. Say "Nothing, just a blue screen." They'll get all crazy and jibber-jabber in the background. Play them along, telling them that you did what they said, and maybe say it locked up your computer, and you'll have to re-boot, etc. Lots of fun. The important thing is to not do whatever they say to do, but tell them you did just what they said, and then yell at them for *******-up your computer, and shout something about their parentage, and maybe, just maybe they'll quit calling!

Steve