That's ingenious!

Never mind. My bad

I hope so. I'm only recently learning SmartPhone and my prepaid plan ( a lot more expensive than yours ) doesn't require monthly usage to stay active. I'm currently learning how to clone my SIM card so I can use them right in my PCs. My old T61P Thinkpad (eBay from $30-$90) has a sim card reader by default and I recently bought a microcard-to-usb dongle that handles several sizes including sims to connect to any PC with USB. So one way or another I think I can do such jobs assuming cloning hasn't been thwarted or tethering queues fail.

Is that even legal??

I am aware that some nefarious folks clone SIMs belonging to someone else to commit illegal acts or to stalk or surveil, but so far I have seen no problems with cloning a SIM one owns. For example, the Smartphone I'm using is one I got from my Son for which he abandoned the phone number about 7 months ago. When I got it, I could read the SIM data and see the old phone number but however the service disables it, it had zero connectivity other than USB, not even wifi. So I can't see how or why that even could be illegal not that all Law make rational sense. I just started researching SIM cloning yesterday so maybe it will turn out badly but I hope not. I can learn a lot from it and would rather not keep swapping around just one SIM. I'd very much like to sometimes be able to handle calls at home through my laptop or PC and leave phone usage to whenever I'm out and about.

Just a bit of an update. I'm no lawyer so I don't know what restrictions may possibly apply, but Amazon, for example, sells Card Readers, including SIM card readers/writers and other's offer cloning software both paid and free. The only restrictions I've stumbled across are for Govt and Military applications. If your credit card(s) have chips, the readers will read those as well. I just don't know what value credit card reading is unless one has some sort of app to work with your bank for accepting credit card purchases and I have yet to see what is mentioned as authentication purposes on any website I've visited. I do like fingerprint readers though, at least for Home use. Perhaps such readers will become more widely used for authentication.

SIM cards? Apparently not a problem since whatever device has one. whether original or cloned, sends the bill to the same account.

I think reading someone's credit card chip could be very useful. It contains the bank sort code and account number in clear, since the payment reader has to send those for checking before it accepts payment. Those are the kind of details scammers like to have.

It also contains your pin, heavily encrypted so that it can't be read. But if someone has watched you enter your pin and has memorised it, he can then clone your card and use the clone.

Naturally I am against nefarious use of such readers for criminal activity but the point is, just because some people are murdered with hammers or kitchen knives that's no cause to create laws against anyone owning a hammer or a knife. In the case of credit card readers they can be a game changer benefit for small business enterprises. So my point was that it doesn't seem likely there will be any laws prohibiting the cloning of SIM cards, but laws against criminal usage may well, should, and likely do exist. That's a good thing.