I haven't answered a single call thanks to a relatively new feature on my iPhone. If you haven't done this and don't know how, go to:
Settings -> Phone -> Call Silencing and Blocked Contacts -> Silence Unknown Callers
Most that try to call will leave me a voice mail message, text or email.
Now if only the FCC and Chairman Ajit Pai can do something about these getting rid of robocalls once for all. They've been annoying us for too long.