I think this is a real number and not one of those fake robocall numbers with the fake caller ID number. It actually lets you call back. Everyone keep calling them and harassing them. Let's turn the tables on these pricks. Don't let these calls go. I never do. I get even.
Same thing happened to me just now; my phone is also on the "do-not-call" list, and I don't have a mortgage either. They asked if they could call in their text, but i'm hesitant to respond even with a "no" because that would tip them off that i exist.