the volume of robo calls purporting to want to verify your location really after... they all offer an option to hit 2 to be put on their Do Not Call list... however, I suspect hitting 2 does something else... does anyone know?
What happens when you hit any key or respond to a 'robocall' is verifying to the computer that called you, that it reached a valid and working number. Pressing 2 to be removed from their calling list, is the call recipients instinct. All that is being done is letting the computer know that it reached a working number. Then your number is shared with other automated calling systems. If you don't recognize the number, do not answer the phone. If it is important they will leave you a voicemail. 9 times out of 10 no voicemail will be left, as computers only generally let the phone ring three to four times before moving to the next number.