If you use an Android phone, here are two settings changes to quickly mute incoming calls. Both of these settings are found in Settings > Sound >Smart Sensor Settings. The first setting, Double Tap to Silence, allows you to tap the screen twice in quick succession to silence the ring tone on an incoming call. The option to answer the call remains visible but there is no accompanying sound. The second setting, Smart Profile: Face Down, allows you to silence an incoming call by simply turning the phone face down. The Face Down setting only works while the phone is ringing. If your phone is face down prior to receiving a call, the phone will still ring.