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.
The call was not taken as someone was on the other line. Have not recieved an email, but they called 3 times in 10 minutes. I am affiliated with Sallie Mae, legitimate call I believe. Identified as Sallie Mae when I called back.