Abstract: The purpose of the invention is to provide a radio-pager that allows a user to set any desired call-sign therein and method of radio-paging that not only conducts person-to-person communication but easily realizes transmission from one person to a plurality (N) of persons such as simultaneous transmission of the same message or commercial massage to a number of pagers. The pager receives radio waves by an antenna, demodulates the received signal into digital data by a radio demodulator and transfers the data to a digital circuit that corrects the data for code transmission error caused by affection of fading. A CPU of the pager examines the correctly reproduced data and extracts a call-sign from the data stream. The CPU 25 reads a call-sign stored in a RAM and examines whether the extracted call-sign corrsponds to the stored call-sign. The pager drives an electronic speaker when the CPU detects that both call-signs are identiacal with each other.

Abstract: A closed user group facility in a data transmission system which has a closed user group of terminals accomodated in a switching network, and in which the switching network registers a terminating terminal in response to a request for registration of that designated terminating terminal from another one of the terminals. The registration of the corresponding terminating terminal is with one of codes with which all the terminals accommodated in the switching network can be individually identified. Subsequently when transmitting data (including voice data) from the originating terminal to the terminating one, the switching network controls to permit the transmission of the data from the originating terminal to the terminating one when the switching network has verified that the originating and terminating terminals had already been mutually registered as distant terminals.