Did not know the number, so I didn't answer.
I do not have an unlimited plan on my cell phone, so it gets annoying. Ny cell is on the DNC list, but they do it anyway.
I didn't answer this call but after reading the posts here, I called it back. It immediately says the survey expired and gave me the option to opt out from all future surveys. Not sure if it will work, but worth a shot to prevent future calls.