This is almost like using my Mac as a Bluetooth headset. An app called HandsFree 2 used to do this beautifully, using Bluetooth to pair my Android and Mac, I could make and receive phone calls without touching my smartphone. I would be working on my laptop and a notification of an incoming call would show and you were able to pick it up and talk only using the Mac.
The app is now discontinued and not working and I haven't been able to found an alternative.
Is there any way to do this?