This is absolutely a scam!  These people got your last 4 digits of your ss # and your drivers license number from either a payday loan application you submitted or maybe a subscription/discount membership.  What I have found so far is that the phone number is serviced by a company called Level 3 Communications.  One of their resellers, AD Base Systems sold this number to a potential customer.  Level 3 Communications is pretty scarey!  They set up/sell telecommunications services all over the US and Europe and I am not just talking cell phones I am talking phones used through the internet and whole call centers.  

Bottom line if you are threaten with violence from this number the first thing to do is call your local police department.  Tell them about the harrassment and the violent threats.  Give them the phone number calling you and tell them that you have managed to confirm the number was sold by AD Base Systems a reseller to Level 3 communications and give them this number to call 800-348-5457. This is the fraud number at Level 3 Communications.  Call them yourself even and report the harrassment.  TELL THEM THEY HAVE AN OBLIGATION  to make sure the services they provide are being used appropriately and not to harrass, threaten, etc.  Once they have been notified of this situation it is their MORAL if not legal obligation to shut the number down.  I think this could turn into a law suit if they do not act upon the complaints they receive.