Patent ID: 8121113

Claim:
A communication system, wherein: said communication system includes a first IP communication network, and said first IP communication network includes plural servers, plural network node apparatuses and a domain name server, a communication between said network node apparatus and a terminal which is outside of said first IP communication network and is connected to said network node apparatus, is carried out by using an external IP packet, and a communication inside of said first IP communication network is carried out by using an internal packet being IP encapsulated, said first IP communication network is connected to a second IP communication network via a first gateway, a terminal T 1 is connected to a network node apparatus N 1 , and a terminal T 2 is connected to said second IP communication network, said terminal T 1 sends a telephone number or host name of said terminal T 2 and a connection request to a server S 1 , said server S 1 sends said telephone number or host name to said domain name server, based on said telephone number or host name, said domain name server finds an IP address of said first gateway to communicate with said terminal T 2 and said domain name server replies said IP address to said server S 1 , based on said connection request, said server S 1 sends a message to said first gateway discriminated by said IP address, and said network node apparatus N 1 receives said external IP packet including voice or data from said terminal T 1 , said network node apparatus N 1 converts said external IP packet into said internal packet including said external IP packet and sends said internal packet to said first gateway, and said first gateway sends said voice or data to said terminal T 2 via said second IP communication network.