Funny how handsfree phones are legal. The law seems to think holding the phone somehow makes it dangerous to drive.
Bullshit. I was phoning someone today because I was late in a traffic jam. Quite a few times I just stopped talking and used that hand to indicate etc. No sane person places conversation high up in priority.
You can explain it to the caller later.
For a long chat just put it on speaker and place it on your knee.