A mobile phone is in fact a small radio. A radio sends a person’s voice over a long way to another radio. A voice that is sent by radio is called a signal. A radio signal travels very quickly.Only a few years ago, mobile phones were very large. They needed large batteries. They had to be powerful to send their signal to far away places. This was because most cities had only one antenna tower for mobile phones.Do you know what use a mobile phone has? Yes, you can use it to do a lot of things.Call your friends and family from almost anywhere.Call the police immediately if there is an accident