Comment by mnemotronic

I'm a little vague on how this works.

So the "bad guys" have loads of SIM cards installed into machines that can make calls or send SMS text messages, right? Doesn't each SIM card require an account with a cell phone provider in order to access "the phone network"? If not then are they getting free cell service and how do I sign up with that (ahem) provider? If so then how were those sim cards paid for? Can we follow the money?