Got this call just now. They called from +1 215-258-8669. Here is the transcription of the voicemail they left me:
"Yes, uh, this is Diana Hughes and I am calling in reference to your Federal student loan. Um, I need to discuss your repayment options with some new changes that have taken effect, so, if you can please give me a call back at 866-317-1811 and then, um, your reference number when you call back is 01017. Thank you."