Fujitsu Corporation

Kazuhisa Shimazaki

Michio Kusayanagi

Akio Morimoto

Koji Tatsumi

Tsutomu Shimasue

Masaaki Ishibashi

Satoshi Namura

Norihisa Uchimoto

Satoshi Hioki

Koichiro Yamada

A first communication device receives an ATM cell bound for a second ATM device from a first ATM device via an ATM interface, and then the first communication device sends a data frame including the ATM cell to the second ATM device via wide area Ethernet. In addition, the first communication device sends a synchronization frame to the second ATM device via the wide area Ethernet continuously at a predetermined time interval in accordance with a clock frequency of the first ATM device. A second communication device receives the synchronization frame and measures a clock frequency of the first ATM device in accordance with a time interval of receiving the synchronization frame so as to reproduce a clock having the same frequency as the measured clock frequency. After that, the second communication device sends the clock to the second ATM device via an ATM interface.

System for supporting communications among ATM devices, device for supporting data transmission, method for sending data, and computer program product

A private branch exchange system having connected thereto a telephone line of a public telephone network, a plurality of extensions, and at least one attendant console. The private branch exchange system has an attendant console control circuit corresponding to each of the attendant consoles in a main frame of the private branch exchange system. A speech signal from a speech path exchange circuit and control signals are multiplexed at the attendant console control circuit to be sent through a transmission line to the corresponding attendant console, and a speech signal and control signals from the attendant console are multiplexed at the attendant console to be sent through a transmission line to the corresponding attendant console control circuit.

Method of multiplexing speech signal and control signal in ISDN

Growing community of inventors

Kawasaki, Japan

Kazuhisa Shimazaki