Open Settings > Phone >Announce Calls. Here, you get to choose whenthe phone announces the caller’s name when it rings: Always, Never, Headphones Only, or Headphones & Car.
The point of Headphones is privacy — it means, “Don’t announce the caller’s name at times when anyone nearby can hear; announce it only when I’m listening in private.”
And the point of “Headphones & Car” is a safety thing. When you’re driving, you don’t want to take your eyes off the road to see who’s calling.