Scammers are criminals, everything they say is a lie.
Your phone number will not be removed from their calling list.
Some robocaller software will flag your phone number as "person present" if you push any number on the keypad, and then call your number more frequently, until a "person present" presses the number to "talk to an agent" who will then begin their lies trying to trick you into giving them the information they want - name, credit card number, Social Security number, etc.
Robocalls are illegal if they are made to a cell phone. No exceptions.
No need to be on any government "Do Not Call" list.