Solving the problem.
I believe that I have solved the problem of talking and driving at the same time.
Very simple, really. When I passed my test in 1995, I did not have a mobile, neither needed one, and I was able to drive from A to B without one.
Nowadays I stick my "all bells and whistles" smartphone in my jeans pocket, and I drive away. No bluetooth, no hands-free kit, nothing. I pretend I don't have a phone while I am in control of car.
I someone calls me, I can call them back later. Simple, really.