It's unlikely you'll get a valid name from this phone number. It could be spoofed. You just can't tell. Where could you get the required back-up data for a civil restraining order, if you can't be sure of the person's name, or even address?
Call could be coming from anywhere.
At this point a call blocker might be your best bet.
Also, if you are getting threats of a criminal nature you should go down to the local police department. Requests for a civil restraining order require a lot of information.