Thanks all for the URLs. I guess the wording is a bit confusing as this Amazon page does not call it a prepaid SIM and whereas PM is a prepaid service, it's not quite what prepaid meant back in the day (20 yrs ago).
Okay, found this SIM card on Amazonhttps://www.amazon.ca/Public-Mobile-Unlocked-Canadas-Subscription/dp/B0CD896ZZHIs it the one I want for my 5g Canada/US/Mex 10GB plan?
It's not a new development, 20+ years old. I'm in contact with them but found out later about buying a Telus SIM. The Amazon SIM link that I found was labelled as a prepaid SIM, not sure that's what I want. Are all PM SIMs prepaid?
