– If disabled, your phone will still ring, but you won't have any on-screen buttons to answer or hang up. Solution: Re-enable it via Settings → Apps → InCallUI (use "Show system apps" if needed).
Because InCallUI handles microphone, speaker, proximity sensor, and screen control during calls, it has extensive permissions. It is a trusted system app; you should never download a third-party “InCallUI” replacement from outside the Galaxy Store or Play Store, as malicious clones exist. what is samsung incallui