They called my cell phone. It rang twice and stopped, so I called them back a minute or two later and a message came on saying that the number was out of service. How the heck do you get a call from a number that is out of service?!!?
---> C G asked, "How the heck do you get a call from a number that is out of service?!!?" <---
That's easy. You either spoof the caller ID, put a message on the voice mail that says the number is out of service, or have your phone company do it for you. (My phone company lets me selectively forward calls to such a message when I get a known scammer calling, for example. It's a privacy measure.)
Just remember, for every bit of privacy YOU think you are entitled to, there's also a scammer out there who will also use it to their own benefit. So it pays to stay alert.