Patent ID: 8462773

Claim:
A default gateway in electronic communication with a plurality of terminal devices and a dynamic domain name service (DDNS) server in a voice over Internet protocol (VoIP) network, each terminal device comprising a telephone number, a corresponding domain name, and a corresponding Internet protocol (IP) address, the default gateway comprising: at least one gateway processor; and a gateway storage system to store one or more programs executable by the at least one gateway processor, the one or more programs comprising: a gateway registration module operable to generate a domain name of the default gateway, and transmit the domain name and an IP address of the default gateway to the DDNS server to register with the DDNS server; a gateway number receiving module operable to receive a called telephone number from a public switched telephone network (PSTN), wherein the called telephone number is the telephone number of a called one of the terminal devices in the VoIP network; a gateway address querying module operable to generate a called domain name corresponding to the called telephone number according to a predefined rule, and query the DDNS server for a called IP address that corresponds to the called domain name; and a gateway signaling exchanging module operable to exchange VoIP signaling with the called terminal device according to the called IP address when the called IP address is successfully queried from the DDNS server, and reject the called telephone number to the PSTN when the called IP address is not successfully queried from the DDNS server; wherein the gateway storage system comprises a plurality of history called IP addresses corresponding to a plurality of history called domain names, and the plurality of history called IP addresses are successfully queried from the DDNS server.