PURPOSE: To efficiently perform the address setting of a terminal and to make it possible to cope with the future function expansion in an exchange network having a packet processing function, particularly in an ISDN network.

CONSTITUTION: An exchange 1 is provided with a network identification code registration table 1a specifying each network address and registering a network identification code having the figure which is smaller as compared with the network address, a detection means 1b receiving the calling request from an arbitrary terminal 3 and detecting the network identification code of the calling destination packet exchange network, a network address discriminating means 1c referring to the network identification code registration table 1a based on the network identification code and discriminating the network address of the calling destination packet exchange network and a control means 1e controlling each part.