I have caller ID, too.  I didn't answer the call and got suspicious.  Sooo glad I did. Left no message, but they must know not to bother now.

Yes they come from all different numbers and you can't call them back.  Infuriating.

caller ID says Michigan call, have got this call many times, I don't answer, they don't leave message. I know have a phone that can block, so I have now blocked this number.

Don't answer calls from numbers you do not know. If no message is left it is most likely scammers. If you can't resist answering. Answer with Detective Division! It really works.

my wife a call from this number on our only phone with out caller id on it.  they asked for me by name saying they were from the new jersey disabled veterans  association , some how they even knew I was a vet. got hostile to her when she told the male she knew his call was a scam and would call our local pd to investigate  them,
hours later our PD did make a post to their face book page warning people of the scam.
hours before I had let another call from the same name and area code and town code go to voicemail where no one left a message, almost like they were looking for live numbers then looked up information on who owns the number