This is very true and very significant. Some claim it is the hand- held unit that is the problem and a headset solves it. Wrong, that is a dangerous misconception. It's the cell phone conversation itself that is dangerous for drivers (and pedestrians, too.)
Also, radio conversations are much more brief and terse:
"GO TO 1234 MAIN STREET, NOW!"
Not:
"yeah, we got a call on Main St., lemme see, was that 4321, 2134, oh, here it is, 1234 Main. Yeah, that's the brick building with those cute hanging plants outside just like my sister has. You remember her, she had that holiday party last year where you got SO drunk? Oh man, you were plastered! My sister was pissed at you! Whaddaya mean I was drunk, too? No way! I had two beers and that was it! And I didn't go around bragging that my girlfriend had the biggest boobs like you did. Anyway, go over to Main St, whereever the hell that was and check it out."
My employer sent those of us who used company cars to a driver training class, taught in the same facilities as police officers are taught in. These had the driving simulator machines. Our course was nothing like a cop's course but it was tough.
Talking on a cell phone and driving ought to be illegal except in emergencies. Plain and simple. I see way too many dangerous mistakes by driver's yakking around, oblivious to their surroundings, even when honked at by motorists. Also, yakkers block traffic by stopping at green lights, going too slowly, and ending up in the wrong lane. At my toll gate there's always a cell phone yakker in the wrong lane messing things up for everyone else. They don't even stop talking when they realize their mistake!
Pedestrians shouldn't cross streets while on their cell phone either. They're just as distracted and a target to get run over.