web browser an im client 503 runs on a terminal 5 and other internet applications 504 including a web browser also run on the terminal 5 fig1 is a sequence diagram illustrating the present invention first as the terminal is activated an os 500 acquires an ip address in the manner quite the same as that shown in fig3 s 101 to s 104 next the im client 503 transmits an authentication request to the im server 8 by using the user name and password s 125 the im client is generally automatically activated when os is activated and the authentication request is automatically transmitted to the server when os acquires the ip address the im server 8 received the authentication request transmits an authentication packet for authentication confirmation to the authentication server 2 s 126 if the user name and password are coincident with those registered in a database the authentication server 2 transmits an acknowledge packet for authentication permission to the im server 8 s 127 if the user name and password are not coincident the authentication server 2 transmits a denial packet for authentication denial to the im server 8 upon reception of the acknowledgement packet from the authentication server 2 the im server 8 transmits a release request packet for releasing policy routing or a change request packet for requesting for a change in a routing control policy used by policy routing to the access server 3 s 128 therefore the packet having the address of the terminal 5 as an address of a.