I called the main number at Sallie Mae's "main number" and apparently, this is one of their unlisted numbers.  It took a while to get a supervisor to search the numbers for me.  Also, 866 994 0395 is one of their numbers.  I am assuming it is a contracted call center, so they intentionally don't show up on caller I.D.'s because the same contractor does debt collections; or at least did in the past.  My best guess at least.  It is always better to be sure and safe.  I.D. theft is growing like mad, I know from working the court system.  Also the number is registered in Indianapolis, IN - so check with the local P.D. or Co. fraud dept. if something really strange happens.