SIGNAL AND SOUND QUALITY - VOICE IS UNCLEAR DURING PHONE CALL?

1. Ensure your phone has a strong signal.
2. Make sure the distance between the earphones and your phone/device is within an optimal range for Bluetooth stereo.
If the above points are met, and you still experience connection problems, you can try to resolve the issue by performing a soft reset and possibly deleting the earphones from the device's Bluetooth memory. See "Bluetooth connection issues".