Today's technology is a lot more advanced and complicated than it was 10 - 15 years ago.
In my own experience, before smart phones, I used to do the SIM swap thing a lot with phones. My phone would die, I would get a used one off Craigslist, swap the SIM, done.
But I found with the tech advances that they now use the ESN for all devices. (Electronic Serial Number) In order to register the phone or similar on another system, such as what you describe here, they have to transfer the ESN along with the SIM.
Be it a phone or other internet capable device, the principle is all the same. Routers and other devices all have their own ESN and specific MAC address.
I quit doing it when it got to the point that I needed to call my carrier every time. It used to be a simple thing but now it isn't.
I am by no means an expert in this stuff, but can relate my own personal experience with the topic.
I think a lot of the refinements and restrictions now in place have to do with criminal activity, theft of smart phones, abuse of services and such things. The carriers all have clamped down on this, and want to keep you married to them and have total control over it all.
It goes a lot deeper than what I describe here.
2007 GMC 3500 dually ext. cab 4X4 LBZ Dmax/Allison - 2007 Pacific Coachworks Tango 306RLSS
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