Abstract

A communication system having an exchange network which can execute a communication procedure necessary for setting of a communication bandwidth with a party variable bandwidth terminal to make the most of characteristic of a terminal which can change its communication bandwidth during communication and to obtain as many call interconnections as possible. The exchange network includes a variable terminal attribute memory device for storing therein the types and ranges of variable bandwidths of the terminals, a bandwidth decision device for determining bandwidths allocated to the respective terminals, and a control data communication device for transmitting at least an allocated bandwidth data to the associated terminal. The variable bandwidth terminal at least includes a control data communication device for receiving the allocated bandwidth data from the exchange network, a line management device for performing access management of lines, and a terminal control device for determining a communication band-width based on the allocated bandwidth data received from the exchange network and the then terminal state to execute a communication procedure with the party terminal and to operate the line management device to increase or decrease the communication bandwidth.