Do you get random phone calls with no one there?

For some reason, every so often I get muliple random calls (I assume robo calls), with a local area code, where if I answer, there is absolutely nothing there.


Most days I don't get any, but then when I do get them, it's like 5 calls in a few hours.


I just don't understand, why is there a call (even a robo call), with absolutely nothing there?