Afortus in call ID. If you call the number it says "Thank you for calling IMF, if you would like to be added to our do not call list please press 2". Problem solved.
Answered after several signals. An automatic voice told me: 'You have been eliminated from this conference.' Couldn't have been more happy about that...
Agreed about it being IMS. That is what showed on my caller id when the call came through a few minutes ago.
If you can block the call (as you can with a mobile phone), do it. But by pressing numbers you are verifying they reached a live person. Unscrupulous parties will not take you off the list. Rather, they sell your "live" number to other solicitors/scammers.