Talking on a cellphone while driving is a convenient, and accepted, part of modern life, especially when it’s done using a hands-free device. By recommending an outright ban on all cellphone use by drivers, the National Transportation Safety Board has instigated a difficult - but sorely needed - conversation about how far lawmakers should go to curb distracted driving, which is estimated to have caused more than 3,000 deaths in 2010 alone.