For one thing, a real attorney is not going to waste his precious time calling any debtor. Period.
So, the person who called was lying.
I had the same thing happen to me when a collection agency called me, and the debt collector on the phone claimed to be a lawyer. In this case, they were actually calling about a debt I knew about. But I knew the guy was not a lawyer, and I had absolutely no intention of ever paying them a dime anyways, so I started cussing at him. And I mean it was vile and disgusting language that I used on him, because he called me. I didn't call him.
He quickly lost his temper on me, and acted very unprofessional. Some lawyer!
And many times I have heard voicemails from various collection agencies that "my account was on their desk" and if I didn't call back right away "they would no choice but to take legal action against me."
Bluff, bluff, bluff.
That's mostly what debt collection is all about.