There is no legal action since they are in foreign countries that ignore our laws and take bribes to look the other way.  Be advised that changing your number can leave you in worse shape since all numbers are recycled.  That means that someone else got rid of their number for the same reason you did.  They may have been getting a ton of telemarketers or debt collection calls.

Threatening call

Was called last night from this number and again this morning, automated message, same crap. Called them back to see how far it would go because I already knew the IRS sends letters out for delinquent taxes, none given. Talked to Officer Frank Jefferson (what's with the presidential money names) heavy East Indian accent with another screaming in the background. Said I owed $3866. I asked him for maybe a reduced rate right away he said $386, then says he has to talk to his attorney, comes back saying $500. He wanted my social security #, if he was with IRS he would have already had it so he didn't get that, then he wanted my credit card # I don't give that out either so he didn't get that. He then wanted me to drive to Walgreens to Western Union it with him on the line 20 minutes away and hand the phone to the clerk so he knew I was there. I told him I don't have a car and he's going to have a long wait. He told me he was going to send an officer out in the morning to pick up the money (I'll be waiting with empty pockets). He kept telling me through the whole conversation if I hang up he'd put the warrant through. He wound up hanging up