A federal court in California recently ruled that Aaron Michael Jones along with nine affiliated companies were responsible for billions of illegal robocalls.  The court issued a permanent injunction against Jones and the companies as well as fining Jones 2.7 million dollars to be paid to the Federal Trade Commission (FTC).
According to the FTC, Jones and his companies made billions of illegal telemarketing robocalls between March 2009 and May 2016 including calls made to people whose numbers were registered on the federal Do Not Call List.  The calls were sales pitches for extended automobile warranties, search engine optimization services and home security systems.
The first defense against phone scammers is skepticism.  You can never be sure when you receive a phone call or a text message as to who is really contacting you.  Even if you have Caller ID, scammers can use a technique called spoofing to make the call appear to be originating from a legitimate source.  Never provide personal information including credit card information to anyone who calls you or text messages you without confirming the legitimacy of the call or text message.  You also may wish to use services like nomorobo  which screens robocalls or Truecaller which screens your phone calls and text messages for robocalls to your smartphone although there have been privacy complaints about Truecaller’s accumulation of data of its customers.