Hopefully it is just scammers. There are a couple of ways that can cause a call with no caller. First, the scammers assume that a certain percentage of their calls will go unanswered so they program their autodialers to call far more people than they can actually handle -- they wind up hanging up on some people, but they don't waste their agents' time with calls that go to answering machines. Or, they may just be "prospecting" for telephone numbers that get answered by real people, and they package that list up for other scammers.
On the other hand, a few years ago I had a miserable experience with a debt collection company. They had bought up an unpaid credit card account and were trying to collect on it. The person involved had the same first and last name as mine, but a different middle name -- and I
always use my middle initial. His last known address was in my town, but on a different street -- and I've lived here almost 25 years. It would have been pretty easy to check these facts out, but not as easy as harassing me in an effort to get me to pay.
They called early in the morning, threatened legal action, finally resorted to yelling at me (and my wife) and calling us unpleasant names.
I finally went online and got the contact info for the Federal Trade Commission. From there I called their offices. They couldn't get involved in my case specifically, but they spent time with me bringing me up to speed on the laws, and how the collections company was violating them. They also emailed me a lot of useful information.
I got one more call from the company, used the info I got from the FTC, followed it up with a letter to the collections company, and the calls stopped.
If you're in the States and have this kind of problem, I strongly suggest you visit the FTC's site.
http://www.consumer.ftc.gov/articles...ebt-collection