Hello,
2 questions:
* Are you using headphones? And if you are have you tried switching them out?
* Have you tried blowing out (GENTLY) the speakers with some air?
''To remove the dirt in the microphone:''
# ''Open some ***compressed air***''
# ''Blow it at the ***grill*** on the top''
# ''Blow into the ***bottom left*** ***microphone***''
# ''Blow into the ***mic at back*** on the right of the camera''
# ''Most of the dirt should be gone so people should hear you''
Another possibility is in your microphone privacy settings:
* To turn on your iPhone’s microphone, go to Settings > Privacy > Microphone > make sure the app you’re using for calls if toggled on.
Another possibility (very rarely) is your network settings try this to reset your network settings:
# From the home screen, tap ***Settings***
# Scroll down to, then tap General
# Scroll down to, then tap ***Reset***
# Tap ***Reset Network Settings***
# Tap ***Reset Network Settings*** to confirm
You can also try to force reboot your iPhone and that may help your situation:
[guide|97574]
Lastly you may need to replace your speaker if all else fails:
[[iPhone 8 Troubleshooting]]
[guide|111548]
Good luck!