Abstract: A method is described of using a mapping between a session initiation protocol (SIP)-Uniform Resource Identifier (URI), local IP address and a global IP address to identify a mobile host attached to a first subnet of a plurality of subnets included in a network domain, receiving a new local IP address of the mobile host upon the mobile host attaching to a second subnet of the plurality of subnets, replacing the local IP address with the new local IP address in the mapping, reformatting routing information of a SIP packet by replacing the global IP address in the routing information with the new local IP address, and communicating the reformatted packet to the mobile host. A proxy server and apparatus for use in this method are also disclosed.

Abstract: A method is described of using a mapping between a session initiation protocol (SIP)-Uniform Resource Identifier (URI), local IP address and a global IP address to identify a mobile host attached to a first subnet of a plurality of subnets included in a network domain, receiving a new local IP address of the mobile host upon the mobile host attaching to a second subnet of the plurality of subnets, replacing the local IP address with the new local IP address in the mapping, reformatting routing information of a SIP packet by replacing the global IP address in the routing information with the new local IP address, and communicating the reformatted packet to the mobile host. A proxy server and apparatus for use in this method are also disclosed.

Abstract: A method is described of routing a packet comprising routing information between a mobile host and a correspondent host in respective first and further network domains, at least the first network domain comprising a plurality of subnets, said mobile host being attached to one of said subnets. The method comprises registering the mobile host with the first network domain, said registration including assigning a global IP address and a local IP address to said mobile host, said local IP address being associated with the subnet to which the mobile host is attached; communicating said local IP address to said mobile host; using the global IP address as the routing information between the domains; reformatting said packet by replacing the global IP address with the local IP address upon receipt of the packet in the first network domain; and communicating the reformatted request to the mobile host via the associated subnet. A proxy server and apparatus for use in this method are also disclosed.

Abstract: A method is described of routing a packet comprising routing information between a mobile host and a correspondent host in respective first and further network domains, at least the first network domain comprising a plurality of subnets, said mobile host being attached to one of said subnets. The method comprises registering the mobile host with the first network domain, said registration including assigning a global IP address and a local IP address to said mobile host, said local IP address being associated with the subnet to which the mobile host is attached; communicating said local IP address to said mobile host; using the global IP address as the routing information between the domains; reformatting said packet by replacing the global IP address with the local IP address upon receipt of the packet in the first network domain; and communicating the reformatted request to the mobile host via the associated subnet. A proxy server and apparatus for use in this method are also disclosed.