Anything that causes the officer to suspect you are not in full control of the vehicle can lead to you being pulled over - using a phone, camera, satnav, road atlas... even drinking or eating a sandwich, because you've only one hand on the wheel
Surely the police can turn on the sirens or talk to their radios then?
I agree that it is dangerous to do somethings while driving but i think the majority of drivers have enough common sense to know when to do and what to do while driving.