Huh. Would it be possible for someone to hijack the SIM card in such a device and use it to get free calls all over the world, including long-distance? Would that be illegal? Would anyone care? :)
There was a case in the news a few years or so ago where someone did that with the SIM that was in their electric meter, which was used once a day by the electric company to send a report of cumulative usage.
What they did not count on was that many cellular carriers have data plans specifically for devices like that electric meter that just need to send a very small amount of data every hour or day or so.
Those plans have a very small monthly fixed fee, a small data allowance, and astronomical overage fees. Typical data allowances for the cheapest plans are maybe 50 KB, which is plenty for sending "<meter-id> <timestamp> <cumulative kWh> <checksum>" once a day.
The person used the SIM for their calls and data, including downloading a bunch of movies. They ended up incurring around $150k overage charges.
The electric company cared very much, and the person ended up with a short jail sentence.
There's an old (10 years?) case about smart traffic lights that included SIM cards for connectivity - which were taken out of the traffic lights and abused. See https://www.bbc.com/news/world-africa-12135841
Another case (for which I don't have a link) some years ago was that ornithologists were doing tracking of large migratory birds using ankle bracelets w. embedded radios - until people "underneath" the birds found out that they contain a SIM provisioned for international roaming, which resulted in birds with such bracelets being shot down to obtain these SIMs as they could be used to extract and sell a few thousand dollars in comms services to locals.
> Would it be possible for someone to hijack the SIM card in such a device
Depends if it's using a physical SIM card or an eSIM module like Apple does that's entirely provisioned from the device's userland.
> and use it to get free calls all over the world, including long-distance?
Depends on the plan assigned by the vendor / phone company. If it's a data only plan, then no.
> Would that be illegal? Would anyone care? :)
Depends on which jurisdiction you are and what you're doing. A couple of dollars worth of charges on a company that sells millions of "smart" devices? Probably won't even get flagged. A couple hundred dollars for calling a phone sex line or someone on a satellite phone however? That will cause someone to have a look.
