I have been getting lots of unregistered phone calls lately. Most of them wrong number who called me up in the middle of my deep sleep all the way from India! It's really irritating especially if the caller doesn't know the meaning of telephone etiquette! And believe me, most of them doesn't.
So if you ever been pestered by anonymous phone calls, I suggest you Report Annoying Callers. Aside from that, there's a great new site where you can look up phone numbers and trace who they are. You can also read lots of commentaries from people who experienced the same annoying situations as you. It's very helpful and informative, and to top it all...it is for free!