This is Navient calling to collect or remind you about your student loan payments; they took over Sallie Mae's old accounts so if you've never heard of "Navient" that may be why.
Everybody knows "Do Not Call" does NOT Work. Try "No More Robot Calls" @ WWW.nomorobo.com. It's a no fee service (for VoiP land lines), eliminated 95 % of my Spam. Check the site . . . it explains how it works and it costs nothing (for land lines) ! [And No, I don't have stock in the company, but I wish I did!]