Final answer:
To use in-vehicle communications equipment cautiously, use hands-free options to minimize radiation exposure, keep the phone away from your body, and avoid using a cellphone without an external antenna.
Step-by-step explanation:
To use in-vehicle communications equipment cautiously, there are several measures you can take. First, use hands-free options like an earpiece or speaker phone to decrease radiation exposure to the head. Second, keep the mobile phone away from your body to minimize radiation absorption.
Finally, avoid using a cellphone in a car without an external antenna, as this can lead to weak signals and increased radiation exposure.