Please try the following:
1. Check if the mute button is on. If so, turn it off.
2. Please contact our Customer Service Centre to check if your phone's microphone is blocked or damaged by foreign matter, dust, or debris.
3. Check the signal strength at both the caller and receiver ends. Poor signal on either end can affect the clarity of sound.
4. Use an earphone suitable for your phone and check if the other person can hear you.
5. Update the phone software.
6. Restart your phone.
If the issue persists, contact the Nothing Support Team for further assistance.