Development of the Personal Handyphone System in Japan At the end of the 1980s, two cordless telephone systems, CT2 and DECT, had entered the second step of their development process. At that time, Japan had not yet developed any comparable technology; therefore work began in 1989 on a Japanese cordless standard, which has become known as the Personal Handyphone System (PHS). Disadvantages of conventional cellular telephone systems, such as high costs of infrastructure and cell-planning resultin