Real debt collectors are jerks, but they are typically trained so as to avoid liability. They do not make the obvious mistakes of claiming cops are on the way, immigration is coming, if you don’t pay right now you are going to jail, etc. They take pains to explain the call is recorded and follow scripts that they sound very bored reading and read very fast. Typically, if you look up the collector online, they will have a business location, business license, and many online reviews saying many negative things.
A scammer will bring high pressure to a whole new level and everything is immediate. They say things like if you don’t pay in the next five minutes we will come to your door, we are waiting outside of your work right now to come in an embarrass you, you are going to jail.
Some scammers will try to adopt the procedures of a real collector and will even try to spoof the phone number, name, business address, and make a fake website. Some impersonate law offices.
The way to handle a scammer is to tell them go ahead and file whatever they are going to file. This is the one thing they can’t do as they are not legitimate and do not have a real attorney who can file pleadings. If it is real and they do file, you have a chance to defend yourself.
Additionally, there is some investigation you can do to verify:
Scammers are persistent and good at their job of scaring you. Just be calm, rational, do your investigation, and dare them to file something. Scammers do not file court pleadings normally and if they do you will have an opportunity to counter sue them.