How to automatically turn on the speaker when move the phone from your ear
Audio routing settings explained
Windows 10 Mobile has new Audio settings in System → Phone. From there you could turn on the vibration when the call is answered, automatically send a text reply, and choose where you want the audio for phone calls.
Go to Settings → System → Phone, and scroll to the bottom of the page. You will see a section called ‘Audio routing’. Tap ‘Audio routing settings’ and you will be able to select an automatic route to the speaker for phone calls, and to choose where to route the audio for incoming and outgoing calls. The first section allows you to select one of Automatic, Bluetooth device or Phone Speaker. Set this option to ‘Auto’ if you don’t use a Bluetooth device, or select ‘Phone Speaker’.
The second option is turned off by default. Enabling this option will automatically turn on the speaker during a call if move the device from your ear.