ACORN has been calling my wife's cell phone (we don't have a land line)number relentlesly, every day of the week. They always call from different area codes and leave a msg about a case number.
You can file a formal, criminal, complaint with your local Police Department. They have the means to track down the all those callers.
I was getting weird 'unknown' cell calls (I'd answer an no one was there). I called T-Mobile and they said I should call the police. That they could find the person, company, or org that was calling.
When that happened to me, I did call the sheriff. They traced it to a relatively near-by location and told me it was likely an automatic dialler used for robo-calls. Now, I simply ask, once, if anyone is there and then hang up. The few times that a number appeared on caller ID, I checked that number on whocalledus.com (from memory, could be an inaccurate URL)and each time it was part of a large phone bank and everyone who posted comments had the same experience of silence after answering.
I have noticed that other calls often begin a few seconds after I answer and are almost always sales pitches, lately for zerO’s various loan adjustment programs. I hang up immediately. We are on the no-call lists for landline (business) and cell numbers. It has cut the number of calls to a minimum.