We are a local business, doing business in S CA.  We have been in business 30 years and had the same phone number for over 20 years.  Can't believe that it's taken them this long to call our office!
We seem to be on every scam/telemarketer/CRIMINAL/Google placement/card processing call list there is.  
I have just blocked the entire 718 area code.
In our office, we have two Digitone call blockers - the first one is full.  
The wonderful thing about the Digitone is that you can BLOCK ENTIRE AREA CODES!!!  
Currently, we have about 55 area codes (throughout the United States) blocked with at least 75 local phone numbers blocked.  
Blocking entire codes is great because the CRIMINAL telemarketers often change 1 or 2 digits or even a prefix number and call again.  By blocking entire area codes, you block all their calls.
We have a particular problem with calls from Washington state.  We now have every area code in Washington state blocked!
The Digitone call blocker also blocks "private/no number" and "out of area" calls as well.  
Our phones do not ring when a blocked call comes in and our office is not disturbed.
Save your sanity - buy a blocking phone (Panasonic now has a blocking phone - 250 numbers) or a blocking device and put these a - holes out of business!