Received a message from this number.  The first part was cut off, but it was obviously a sales call for some sort of system.  "This system is absolutely free," was part of the message.  Then "press 1 for more information or 9 to be placed on a "do not call" list."  Yeah, like I'm going to press 9 to validate my number so that you scumbags can sell me to another company on your scummy marketing list.

Answer the phone silently, and don't say a word.  Eventually, your number will get dropped.  Or invest in one of those robocaller devices that blocks those calls.