Data terminal control unit including table for efficiently making connections between data terminal equipments and between data terminal equipment and outside lines

摘要

A plurality of data terminals are connected to a plurality of ports in a data terminal control unit. A table representing correspondence in an extension number, a dial-in number and an ISDN subaddress of each data terminal equipment, the number of a port connected with each data terminal equipment, and so on is provided within the data terminal control unit. When one data terminal equipment calls another data terminal equipment, the extension number of the data terminal equipment to be called is set in a setup message. When one data terminal equipment is called from an outside line, an ISDN number thereof is set in a setup message. The setup message is then transmitted to the data terminal control unit. The data terminal control unit refers to the table, thereby to specify the data terminal equipment to be called and transmit the setup message to the corresponding data terminal equipment.