It is an express violation of the FDCPA to threaten arrest for an unpaid debt.
It is also a violation to make any representation that a communication is from a federal agency.
See FDCPA 807.
I would also send notice to the CFPB and your state office of the AG for inclusion their databases.
You also have the right to bring civil action to recover statutory damages of $1,000 per violation of the FDCPA.
But do they ever catch any of these scammers? I remember reading recently that they broke up a big ring in India, but that first caller was stupid enough to leave a message & call back #, must be a rank amateur. But the 2nd call is showing up on a google search as a wireless # in the bay area, so likely a spoofed call ID - with an internet phone service you can put in anything as a caller ID.
It is important to notify the governmental agencies, such as the FTC, CFPB, or state AG, of such issues in that multiple complaints for the same practice will often be basis for their initiation of an investigation. They normally dont investigate individual consumer complaints, and thus multiple instances are usually necessary to bring about action.
As for chances of results, only government agencies obtain data via inputs from mulitple sources, and then have the resources or authority to conduct a full investigation, such as tracing phone numbers, etc. If the govenment agency ever does bring action, those who have filed complaints are likely to be included in the class of consumers eligible for damages or agreement to pay once a civil judgment or consent order is reached.
It appears that a lot of these scam operations hop around from number to number and call people more or less at random to try to trick, browbeat or threaten them into giving them money or at least their personal financial information. I got several calls last week from a number in my area code, for example, and on Googling it I found that everyone who reported it to various "who's called you?" services described it, without exception, as a scam/junk number - in fact a lot of the time there wasn't even a live person answering. Never return a call to any number that you can't find the owner/user, doesn't appear to be legitimate when you look it up or don't have any reason to be expecting a call from until you can verify it by other means.
I got hit with a scam call yesterday..
caller: Your son has been in a terrible accident here in Mexico
me: My SON??? OMG (sarcasm)
caller: Your son D...., he is badly injured and you need to wire $3,000 immediately for his surgery...HE WILL DIE if you don't send it
me: WOW, well you see I never really liked him and he's insured with me as the beneficiary...My vote is to let him pass peacefully
caller: you evil lady (and hung up)
I guess they didn't expect that from me ROFL...and by the way son D.... is safe and happy north of the mason dixson line