Block the number. For a smart phone you can install a free call blocking app. For a land line you can buy and install an electronic device that blocks calls.
For a simple cell phone ask your carrier. Or put the pest in your contacts list and give them the ring tone "no ring" or "silence". That will send the call to voice mail without ringing.
SSDD. Robo calls from dummy numbers looking for live bodies to sell to other people.
Dialed number and it stated: Press 9 to be placed on the do not call list. No other information available, and I keep getting periodic calls from various numbers that this scamming company makes up- no message left ever.
My recommendation is to ignore the calls and never call them back- you won't be able to get rid of the spam calls after that!