Who called from 5863072000

For 3 weeks I have been getting messages on my phone from this number.  It is a beeping fax machine.

called me during class and i called this number back and it said it was disconnected

I received two phone calls from that number. It called to my cell phone. I called back on a different phone. It said, "disconnected." Then, that phone called to the phone that I used to call out three times. I picked up. It only said "Thank you, Good Bye", then hung up.

It's from the ANG base in Sulfridge, it is their outgoing exchange - that's why you can't call it back