PURPOSE: To realize inter-network connection with a simple operation procedure and at low cost in an inter-network connection method by which the call of inter-communication network is set/released.

CONSTITUTION: In inter-network connection, a call-side transmits call control information in a self network and call control information in the other network as other network information to a station having an inter-network connection function in the self network. The station of the self network is connected with the station having the inter-network connection function in the other network in accordance with reception information, extracts other network information among reception information and treats it as inter-network information so as to transfer it. In the other network, an incoming call-side is connected in accordance with other received network information.