It is really dangerous to talk on a mobile phone while driving, but most people doesn't realise it or care about it. As long as it is legal in Australia. I saw a lady killed a bicycle boy because of typing sms message when she was on the road. A lapse in concentration while driving can kill. My old mobile has "auto answering in the car" function. The person on the other end may not know what situation you are in, so please do not answer or just tell them. Involving in a car accident will take much longer time than calling back afterwards...
Just a reminder...b'coz ust had a 5 mins conversation with someone who was driving....