This invention is comprised of a telephone exchange having a memory for storing a telephone number and a personal data corresponding to the telephone number; a telephone set stored in the telephone exchange; and a portable information terminal having a memory for storing the telephone number and personal data corresponding to the telephone number, wherein when the portable information terminal is installed in the telephone set, the content in the memory in the telephone exchange is collated with the content in the memory in the portable information terminal and the contents in both memories are coincided to each other.