Just got one too. Have no idea

I called and got "Not in Service" message.

Whenever you get a call, then call back and get a recording that the number you called is "not in service," it's a scam or telemarketer call. Block it!

they reported themselves as a mortgage company....

This is some kind of debt consolidation service, making random calls in violation of the National Do-Not-Call Registry (sounded like a very busy OVERSEAS call center, so out of reach of any U.S. prosecution). I agreed that I had over $10k in unsecured debt (!), and gave bogus info about my family, where the debt is and my work status. They will give the info to the loan companies in the States who are employing them in order to skirt the NDNCR - when these companies call, I'll waste as much of their time as possible, giving more bogus info, and after a loooooong while let them know that they HAVE BEEN PUNKED for using a law-breaking third-party entity and that this implicates THEM in the illegal activity. I also tell them that I hope they like spending a good chunk of their day being a Punkee, because lots of folks are not happy with the constantly ringing phone and are starting to fight back...