Fujitsu Corporation

Yoshiharu Kano

Takashi Matsumoto

Yoshikazu Tanaka

Shigehiko Yazawa

Hiroshi Ozawa

Masaharu Matsumoto

Shoji Nojiri

Kazushige Haruta

Makoto Fujisawa

Disclosed is a communication system which improves the system flexibility and serviceability by efficiently controlling presence information. A presence inquiring section makes an inquiry about a presence state of a communicating party. A presence information receiving section receives presence information. A presence information display section displays the received presence information. A presence determining section determines the presence state. A presence information generating section generates the presence information. A presence information sending section sends the presence information upon reception of the inquiry.

Communication system

A digital time-divison switch comprising a multiplexer which multiplexes digitalized voice signals, supervisory signals transmitted from line circuit portions, and so forth, and which inserts these signals into predetermined time slots. The digital switch also includes a signal-extracting circuit which extracts the supervisory signals from the time slots assigned for control signals and which transmits the extracted supervisory signals to a common control unit through the supervisory signal receiver, a switching network which switches data time slots, a signal inserting circuit for transmitting control signals to the line circuit portions, and a distributor circuit for distributing the voice signals and so on to each line circuit. The switch further includes a second signal-inserting circuit disposed between the signal-extracting circuit and the switching network, the second signal-inserting circuit inserting one-way signals transmitted from a switching network portion to the line circuit portions into the time slots assigned for control signals, in the other words into time slots into which supervisory signals extracted by the signal-extracting circuit are previously inserted.

Digital time-division switch

Growing community of inventors

Tokyo, Japan

Yoshiharu Kano