Why can't I hear sound from the camera during a call?

1. Whether to enable the mobile phone to allow the App to use the phone's microphone;

2. Whether to turn on the voice intercom function of the App video interface;

3. Remove the device from the App and re-bind the camera;

4. Check if there is sound when recording video on the SD card of the camera. If there is no sound, it may be a malfunction of the camera's microphone or speaker.