True, but your callers are more likely than not to be located in India. They are hard core scammers and ignore all US laws.
Call blocker is your best bet and do not pick up on calls you do not recognize.
Repeatedly calling me and not a single soul speaks good English. They are pushy, stating they are from some kind of medical compensation. I had nothing better to do so I called back 25 times until they promised to remove me.
I just received a call today and I usually don't pick up. I ended up calling back after I saw a previous post here about it being a "medical compensation." The person who answered sounded like English is her Secondary language. I mentioned I had a missed call. She then went on, without even asking who I was, that I had some time of surgery and I have a medical compensation. I quickly told her I've never had any surgery and it's the wrong number. She hung up. She didn't even introduced herself on what company she's from. This is not a real medical compensation call.