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Try These Quick and Easy Fixes to Get It Working Again!
Remove any headphones or earbuds to check that Siri responds directly through your iPhone, as connected audio devices can interfere.
Disconnect Headphones/Earbuds
If headphones or earbuds are still connected, Siri might be routed through them. Check and disconnect via Control Center or Bluetooth settings.
Check for Bluetooth Connections
In Settings > Siri & Search, make sure "Listen for 'Hey Siri'" and "Allow Siri When Locked" are both turned on.
Check That 'Hey Siri' is Enabled
If Siri isn’t responding well, retrain it by turning off and re-enabling "Listen for 'Hey Siri,'" then follow the setup process again.
Retrain Siri
Make sure that your phone’s microphone is clear of things like dirt or dust, and not covered by a case or screen protector.
Check the Microphone
To have Siri respond even when your phone is face down, go to Settings > Accessibility > Siri, and turn on "Always Listen for 'Hey Siri.'"
Use Always Listen for Siri
A simple restart can fix software glitches and restore Siri’s functionality. Press and hold the power and volume button, slide to power off, then restart.
Restart Your iPhone
If multiple devices respond to "Hey Siri," make sure Bluetooth is connected on all devices so the closest one responds.
Fix Multiple Devices Responding to 'Hey Siri'