iphone 6 no sound during calls

Hello there, quodat89.

It seems your issue is that you are unable to hear sound from your iPhone, unless you use your EarPods. The following Knowledge Base article offers up some great recommendations for troubleshooting:

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

Follow these steps and test the sound after each one.

1. Go to Settings > Sounds and drag the Ringer And Alerts slider to turn the volume up.
2. If you can hear sound from the speaker, then the speaker works. Continue with these steps to find the setting or switch that's affecting the sound. If you can't hear sound from the speaker, contact Apple Support.
3. If your device has a Ring/Silent switch, make sure it's set to ring. If you can see orange, it's set to silent.
   
4. Restart your device.
5. Open an app that has music or sound effects. Adjust the volume with the volume buttons or the slider in Control Center.
6. Go to Settings > Bluetooth and turn off Bluetooth.
7. If there's still no sound, connect a headset. If you can hear sound through the headset, remove it and clear any dust or debris from the headset jack of your device.
8. If the device is in a case, make sure that the case doesn't block the speaker.
9. Use a brush to gently clear any debris from the speaker and Lightning connector (or 30-pin dock connector). The brush should be clean and dry and have soft bristles.
10. Update your device to the latest version of iOS.

If you follow these steps and still hear no sound or distorted sound, contact us.

Thanks for reaching out to Apple Support Communities.

Cheers.