I have a Samsung Galaxy phone. Over the last few weeks, I've started getting waves of calls from a rotating series of numbers. For instance, today I get a call from "111". I block the caller. A few minutes later, I get a call from "222", a few minutes later "333", and so on. And so on. There is no actual call per se. It terminates as soon as I answer. So, it's not for the purpose of selling me anything. Apparently, it's just phone-trolling. But the real kicker is that my provider, Sprint, doesn't have any record of these phone calls. How can I be called without going through my provider? Google turns up no information on this particular type of robocalling. Would at least be helpful if I knew what this type of attack was called. Anyone familiar with this?