Got a hang-up call from a Cell Phone listed as 360-529-6164 on my caller ID. No message. No recording. I classify any phone call that doesn't involve a message or attempt to speak as a prank call, because that is literally what they are. You call someone because you are trying to reach them, not to hang up on them without a comment of any kind.
In my opinion, such calls should be fined heavily. If it cost them enough, they would stop doing it.