n be converted to sound that is comprehendible to us humans, but
             These telephones are big and bulky and they need wires to transmit these pulses. Then
             Came the invention called A cellular telephone that designed to give the user maximum
             Freedom of movement while using a telephone. A cellular telephone uses radio signals
             To communicate between the set and an antenna. The served area is divided into cells
             something like a honeycomb, and an antenna is placed within each cell and connected
             by telephone lines to one exchange devoted to cellular telephone calls. This exchange
             connects cellular telephones to one another or transfers the call to a regular exchange
             if the call is between a cellular telephone and a noncellular telephone. The special
             cellular exchange, through computer control, selects the antenna closest to the
             telephone when service is requested. As the telephone roams, the exchange
             automatically determines when to change the serving cell based on the power of the
             radio signal received simultaneously at adjacent sites. This change occurs without
             interrupting conversation. Practical power considerations limit the distance between
             the telephone and the nearest cellular antenna, and since cellular phones use radio
             signals, it is very easy for unauthorized people to access communications carried out
             over cellular phones. Currently, digital cellular phones are gaining in popularity
             because the radio signals are harder to intercept and decode. Also the fast growing
             popular video phones that work like a normal telephone but includes the ability to
             transmit videos through the use of a small camera. although these video phones are
             not yet popular in our present society. they will soon be in every home in the world.
             not all inventions that where once practical remain practical. one example are the
             invention of pagers. although these pagers are still currently used in our...