I actually don't even answer the phone when it is people in my own organization most of the time. Partly because like you said, they just want something, but mostly because they don't know how to forward calls properly. Even though it shows as them it might be a forward from an outside line, then I get stuck talking to a sales person. I get DMs too, but probably not as many as you do. I just ignore most of them.
The ultimate scammed!
I don't get why they don't understand that there are better ways.