Most car-based phones are speakerphones, which allow you to keep your hands on the wheel while speaking. Making a call can be dangerous, particularly when in traffic. The function key accesses most of the carrier-supplied services. Most phones have security features that block outgoing calls to certain numbers without a password. Cellular phones have volume controls for the ringer, keypad tones, function and alert beeps, as well as a muting feature.
Many features are accessible through a menu listed on the display panel.
Because securing the handset is an issue in a moving vehicle, there is wide difference in the ease or difficulty of removing or replacing the handset to and from the cradle. Some require a button or latch be pushed to release the handset, a method paradoxically called quick-release latches. To return the handset many phones need maneuvering into place, others use a magnetic seal. Transportables are low-power phones, usually only three watts. They are designed to be used in one location, not while in motion.