Who Are These People?

Yesterday our home phone was deluged by calls from people who had received a call from “our phone” and, having caller ID, returned the call to see what was up. After some confusion it was determined that a telemarketer in Missouri with a similar, yet different number, was computer-dialing (my term there) people with some sort of offer. Dozens – probably close to one hundred called “back” to our home to see what was up.
Amazing – who calls back a telemarketing computer-generated call? Not too long ago everyone was up in arms about telemarketing calls and the various state and federal “no-call lists” were implemented to thunderous approval – or so I thought. Apparently there are a lot of gullible people out there who not only welcome telemarketers’ calls, but also go to the effort to contact them back after they missed the call.
I wonder what they were selling?