When they call you, they have to get you to acknowledge who you are. If they ask to talk to "John Jones", and you say "I am John Jones", they've "got you".
They will then tell you that you owe whatever it is they think you owe, and if you don't pay, they are allowed to ding your credit report with a collection entry. So DONT SAY "I AM ....." and give your name. If they ask you "ARE YOU JOHN JONES?" DONT SAY YES. Don't say YES at any time during the call because they will piece together them asking you "ARE YOU .....", and your YES to some other question they ask, and "they've got you".
That's the law, but they don't care about that. They have called me several times, but I never acknowledged who I was.
They finally got tired of trying and put a collection entry on my credit report anyway. ILLEGAL TO DO THAT.