How does a telephone handset change the incoming signals from a caller into sound that you can hear?

A telephone handset converts incoming electrical signals into sound through a process called transduction. The incoming electrical signals, which represent the caller's voice, are sent to a speaker (or receiver) in the handset. This speaker uses a diaphragm that vibrates in response to the electrical signals, creating sound waves that mimic the original voice. These sound waves then travel through the air to your ears, allowing you to hear the caller.