Patent ID: 8238331
Filing Date: 2012-08-07
Classification: H04L,H04Q

Abstract:
1. A communication system comprising: a network address translator (NAT) router configured to connect a private network, and a global network which is arranged in an area broader than the private network; and a telephone exchange apparatus connected to the private network, and configured to establish communication between terminals, wherein the NAT router comprises a forwarding table configured to store a data in which an address and port number of the NAT router and an address and port number of the telephone exchange apparatus are correlated with each other, and transfers a communication packet brought from the global network to the telephone exchange apparatus, based on the forwarding table, the telephone exchange apparatus comprises a memory configured to store a map table in which a terminal ID specifying the terminal, and an address and a port number specifying the network are correlated with each other, and a controller configured to refer to the map table in communication connection between the terminals, determine whether or not there is the NAT router between the terminals connected to each other by the communication based on a reference result of the map table, read out information indicating record contents of the forwarding table from the NAT router, when the controller determines whether there is the NAT router, record information indicating record contents of the forwarding table in a relay resource table, notify the terminal connected to the global network of an address and a port number of the NAT router's own apparatus as an address and a port number of the communication partner based on the relay resource table, and establish the communication path between the terminals via the telephone exchange apparatus.