Hands-free systems are telephone systems that allow the person making the call to speak freely without lifting the handset.
Hands-free systems are mandatory for car-to-mobile communication( C2M) in motor vehicles when the driver wants to make phone calls while driving. Hands-free systems for cell phones are adapters that are mounted in the motor vehicle and are equipped with a microphone and loudspeaker. They have a mute function that turns off the volume of the car radio when the phone call is answered.
Hands-free devices in cell phones and smartphones are equipped with a microphone and speaker and allow hands-free calling. This allows people in the vicinity to participate in the phone call.