The numbers are associated with Discover. Answered the call on my cell phone from AZ and they took me off their calling list...so far so good. They were actually looking for another person. The 800# disputes existence of these numbers as being theirs because they don't want anyone to know about their "call centers".
We ignored Discover's many calls (even early morning, late night) for weeks until I finally answered. Nice young lady said Discover was offering a "service" of some kind but she said she'd remove our number from their calling list. No collections -- our account is up-to-date.