The document traces the evolution of cell phones from their origins in the 1920s using radios for police communication to the development of the first portable handheld cell phone by Martin Cooper of Motorola in 1973. It describes how early cell phones were large and expensive when first available to the public in 1984. The establishment of cellular networks in the late 1960s and 1970s enabled cell phones to work by passing calls between towers. The document then outlines the progression to smaller 2G digital cell phones in the 1990s and today's feature-rich 3G smartphones.