Patent ID: 8601161

Claim:
An address translation method between a IPv6 network and a IPv4 network comprising the steps of: receiving an IPv6 packet conforming to an IPv6 protocol from the IPv6 network, the IPv6 packet including a first portion and a second portion, the first portion including an IPv6 header having a first IPv6 address, the second portion including a first SIP message having a second IPv6 address; translating the first IPv6 address in the IPv6 header to a first IPv4 address according to information for translating from an IPv6 address to an IPv4 address; obtaining a second SIP message including a translated second IPv4 address, the translated second IPv4 address having been translated from the IPv6 address included in the first SIP message of the received IPv6 packet; creating a IPv4 packet including an IPv4 header and the obtained second SIP message, the IPv4 header including the translated second IPv4 address; and transmitting the created IPv4 packet to the IPv4 network.