I'm not certain these are satisfactory answers.  It feels as if we are on the defensive and the spammers are winning.  The DNC list is apparently poorly enforced or ineffective for some other reason.  This is particularly annoying when applied to text messages where we, as recipients, wind up paying for the spam. 

At this point I'm uncertain what steps are practical as a means of preventing this type of abuse, but I would appreciate a report from Verizon or perhaps all the telecoms assuring us that there is some concern and some constructive steps, whether via technology or law enforcement, are being taken.