It may happen that you need your phone speaker to be the default device when making / receiving calls instead of the earpiece. Windows 10 mobile now allows you set your speakers to be default when you make /receive calls.
- Navigate to Settings
- Tap on System.
- Tap on Phone.
- Scroll down to “Audio routing”.
- Tap on “Audio routing settings”.
- Select “Phone Speaker” under “Choose where you want audio to play when making or receiving phone calls”.