issue or error

Hello Linnkhantkyaw,

Thanks for asking the Apple Support Communities for help with hearing callers through the main receiver. Please go through the troubleshooting in these two help articles:

If you hear no sound or distorted sound from your iPhone, iPad, or iPod touch speaker - Apple Support

If your iPhone is stuck in headphone mode - Apple Support

You also mention that microphone isn't working. Please go through the troubleshooting here: If the microphones on your iPhone aren't working - Apple Support

Thanks and have a wonderful day.