Robo-call from Direct Buy, a notorious company that has one of the worst reputations of any company in the USA. They are not only reportedly abusive, corrupt, and deceitful in their business practices, they also wantonly violate the Do Not Call list. I contacted their corporate office but they don't care.
Nope. You're assuming everyone knows which numbers are cell phones and which ones aren't, which isn't true. All the same, the Do Not Call registry applies to all phones. Register your number there!