These people call EVERY DAY and when I answer the phone, there is no one there, only a message saying they were sorry no one was available to answer my call back. They don't leave messages. I am on the DO NOT CALL LIST for whatever good that is as we still keep getting numerous calls from telemarketers, now, especially for switching electric companies.
For a scammer the Do Not Call List law is just one more law to break. If they calls are that annoying you can buy a call blocker for your land line or a call blocking ap for your cell phone.