Just got a missed call from this number.

I'm blocking this number. They called me today and left no vm.

Called but left no message. Called them back. Debt collector.
They said my number wasn't listed as having an active file with them. Since they didn't leave a message, they couldn't look it up to see why they called me. Still don't know who they were looking for.

Caller from Navient, which may be monitored or recorded. I imagine if the employee wanted a call from them at work, he/she would have given them his/her direct line.

Navient is a student loan provider, formerly known as Sallie Mae.