When is it acceptable to use a cellphone while driving a commercial vehicle?

Using a cellphone while driving a commercial vehicle is generally subject to strict regulations to ensure safety on the road. The correct answer indicates that using a cellphone is acceptable when it is hands-free and the vehicle is not moving. This is important because it allows the driver to maintain full control of the vehicle and keep their attention focused on driving, thereby reducing the risk of accidents or distractions.

Hands-free usage allows drivers to communicate without physically holding the phone, which can distract from the primary task of driving. Additionally, by being stopped (not moving), the driver can engage in conversation without compromising their ability to respond to the road conditions around them.

The other options imply situations where cell phone use could lead to distractions that may negatively impact driving. For example, dialing a number, being stopped at a traffic light, or using a speakerphone may not fully mitigate the risks of distraction. Thus, the most responsible and safe practice within the context of commercial driving is to use a cellphone in a hands-free manner while the vehicle is stationary.