| 摘要 |
<p>PURPOSE: A head end device for a VoIP(Voice over Internet Protocol) call service with an MGCP(Media Gateway Control Protocol) type is provided to minimize public IP insufficient phenomenon and offer a data communication service and a VoIP service in a VoIP network which provides the VoIP service to a plurality of subscribers who use a data communication terminal together with a VoIP terminal. CONSTITUTION: A DHCP(Dynamic Host Configuration Protocol) server(206) assigns a public IP address to data communication terminals, and assigns a private IP address to VoIP terminals. A router(202) routes an IP packet transmitted between the data communication terminals and the Internet(116), uses an IP address of a call agent(118) or a gateway(120) as a designation address, and blocks a received IP packet having a UDP(User Datagram Protocol) packet. If an IP packet having a source IP address with a private IP address, a destination IP address with the IP address of the call agent(118) or the gateway(120), and the UDP packet is received from the VoIP terminal, an MGCP NAT(Network Address Translator) router(204) changes the source IP address of the received IP packet to a public IP address, newly assigns a UDP port number, and transmits the IP packet to the Internet(116). The MGCP NAT router(204) registers IP addresses and UDP port numbers in a conversion table. If an IP packet having the source IP address with the IP address of the call agent(118) or the gateway(120) and an UDP port number registered in the conversion table is received from the Internet(116), the MGCP NAT router(204) changes the destination IP address and the UDP port number of the received IP packet to the registered private IP address and UDP port number, and transmits the IP packet.</p> |
