Conversations of any kind (with or without the involvement of the hands) impair concentration and reactions in braking tests. For some reason the brain treats a telephone conversation differently from talking to a passenger, perhaps because the passenger is also aware of possible road hazards in a way the telephone caller cannot be and so makes less demands upon the driver in terms of concentration at critical moments. In any case, voice activated technology is often unreliable, risking drivers trying to use it getting frustrated and losing concentration. It would be inconsistent to ban one sort of mobile phone while allowing the other sort, which can be just as lethal. Therefore, hands-free mobile phone use while driving should also be banned.  Further, "Some researchers, in fact, fear that the new law may cause more traffic accidents, not fewer, because they envision more distractions for many motorists. When ring tones chime and drivers scramble to find their newly purchased headsets -- or, alternatively, scan the roadsides for police enforcing the new ban -- their attention, already stretched, will be further taxed. [1]  [1] Healy, Melissa. “Hands-Free cellphone use while driving won’t make the roads safe, studies show. Why? Brain Overload.” 30/06/2008