The headphone line control calibration operation is as follows:

1. Click the volume: increase the music or call volume.

2. Click Volume-: Reduce the volume of music or calls; mute the sound during incoming calls.

3. Click the middle button: play/pause music; answer an incoming call, hang up during a call; automatically take pictures in the camera interface.

4. Double-click/triple-click the middle button: next/previous music.

5. Press and hold the middle button: reject an incoming call; activate the voice assistant when unlocked.