Conversation VS phone call

"A conversation with a passenger is just as demanding as a telephone call. However, there may be an interaction between you and your passenger when talking to one another. This interaction is based on your passenger also being focused on the traffic. In a difficult traffic situation, your passenger will probably not ask you any questions, and will not find it strange if you do not answer at once."

Driver license handbook

Handsfree

"A driver using a handsfree will be more or less as unfocused as a driver holding a mobile phone in their hand. Their reaction time will be much longer and their driving as uneven as when talking on a hand-held device."

Driver license handbook