Many of these calls are coming from Costa Rica and India and they are using spoofed (false) numbers, which in itself is illegal. They do cold calling for or sell the leads to numerous companies in this country and they all know that what they are doing is illegal. Tomorrow this same number may be selling Cruises, Timeshares or Security Systems but if you follow the money it usually ends up in the hands of an American LLC.
Most of the inbound robo call numbers are spoofed, as most of the bolierhouses, both off and on shore, are using Voip SIP Trunks services. Throwaway DID numbers are also used. Some of the robocalling is operated by the end use scammers directly. Others are contract services who earn a referral fee once you are transferred to the scammers.
The criminals behind this operation aren't going to pay attention to you asking to be removed from their list. Their calls cost them almost nothing and they make millions of them so they have no intention of ever removing someone. When you press a key to talk to them all that is accomplished is to verify that they have a working number.
Unfortunately blowing an air horn or whistle doesn't work either. Their headset have noise dampeners plus they are expecting it. However with that said if it makes you feel better then by all means give it a shot.
The banking system is also at fault here, without merchant accounts and ACH processing these criminals could not collect the scammed funds. Though the criminals use obfuscation, layered corporations, multiple bank accounts and offshore stashing, patterns of obvious fraudulent activity become apparent after a very short time.
This is an all out attack from these scum suckers! EVERYONE should be reporting them everywhere that they can. Since this is an obvious attempt at identity theft the FBI should be forced to get involved. (Prosecute them in criminal court instead of civil penalties).
If you want to stop these calls then you need to dry up their revenue source. Your phone company is charging you a fee for Caller ID. Your phone company pays the scammer for sending their Caller ID information. Your phone company pays only a fraction of a cent per call and you pay your phone company to have the Caller ID displayed. The scammers send out millions of calls which amounts to a significant amount of money however your phone company is charging a large amount to millions of customers. This may have something to do with the phone companies inability to stop these calls.
In order to stop this we need legislation making it illegal to charge for caller ID. If a phone service wishes to operate it would need to provide the Caller ID at no charge as part of the service. Here is the $50,000 solution that the FCC is looking for and it doesn't cost anything.
There is an excellent blog site that I found that explains how one company is getting away with this activity.