Ensure your speaker is turned on. If you see the speaker icon in the top-left corner is turned off, tap it to turn on your speaker.
1. Increase the volume on your mobile device using the volume buttons or notification panel. Even if the speaker is turned on in Zoom, your device’s volume might be set to mute or vibrate only.
2. Try using earphones.
3. Restart your mobile device.
4. Reinstall Zoom from the Apple App Store or Google Play