1. Check that your microphone is not muted. Also, restarting your phone could resolve the issue. To do that, hold the Power and Volume Down keys simultaneously until the phone vibrates. Release and the phone will restart.
  2. Check that the microphone opening is not blocked. To find the microphone opening, refer to your phone user guide.
  3. Move to a quieter area.
  4. Set your phone to loudspeaker mode, or try a wired headset that has a microphone.
  5. Check if the issue is with a specific number on outgoing or incoming calls.
  6. Use the volume keys to adjust the volume.
  7. Test your phone's microphone and speakers with the pre-installed voice recorder. To record a clip, go to Messaging > New (+)Attach and tap voice note. Record an audio clip, and play the recording. If you can hear the recording, your microphone is ok.