Got a call from them this morning at 4:30 AM.
Caller ID displayed NETPROWA.
Voice mail message was just beeps for at least 30 secs.
It is possible that this may have been from a FAX machine.
This number has been calling my work phone consistently for months, maybe even a year. As everyone said, Caller ID says NETPROWA and just beeps whether I answer or leave for voicemail.