A cell phone is any portable telephone which receives or sends messages through a Cell site, or transmitting tower. Radio waves are used to transfer signals to and from the cell phone. Each cell site has a range of 3-5 miles and overlaps other cell sites. All of the cell sites are connected to one or more cellular switching exchanges which can detect the strength of the signal received from the telephone. As the telephone user moves from one cell area to another, the exchange automatically switches the call to the cell site with the strongest signal.
The term cell phone is uncommon outside of the US. Even in the US, cellular technology only refers to one kind of mobile phone technologies among many. Hence it is a misnomer to use the term 'cell phone' to cover all mobile phones, but many people do.
See mobile phone