The law is hotting up on drives who use mobile devices whilst driving. It is against the law to drive a car whilst using a mobile phone, unless it is using a hands free device. There is still quite a valid argument though that using a hands free device is still not completely without risk and may not be as safe as you would like to think. You are certainly better off not to use your phone at all, but often this is not possible especially for people like reps etc who need to be able to have the ability to make and take phone calls when on the road all day.
There is a huge selection of hands-free devices out there which range in price and functionality. If you have a stereo that has an aux port on it or a micro