Patent ID: 8661097

Claim:
A service node configured to serve a first user node in a first network, wherein the first network includes a control node and is configured to communicate with a second network including a second user node, the service node comprising: a request receiving circuit configured to receive, from the first user node, a redirection request including a first user identity that identifies the first user node in the first network and a second user identity that identifies the second user node in the second network, the redirection request requesting that messages directed to the first user identity be redirected to the second user identity; a storing circuit configured to store an association of the first user identity and the second user identity; a message receiving circuit configured to receive a message from the control node; a determining circuit configured to determine whether the message includes the first user identity as a destination of the message, or whether the message includes auxiliary information that corresponds to the first user identity; a modifying circuit configured to: modify the destination of the message to be the second user identity, based on the stored association, if the determining circuit determines that the message includes the first user identity as the destination, and modify a source of the message to be the first user identity, based on the auxiliary information, if the determining circuit determines that the message includes the auxiliary information; and a sending circuit configured to send the modified message to the control node; wherein: the first network is a first IP Multimedia Subsystem (IMS) network; the second network is a second IMS network; the first user identity is an IMS Public User Identity (IMPU) of the first user node; the second user identity is an IMPU of the second user node; the message is a Session Initiation Protocol (SIP) Request message; the control node comprises a Serving Call Session Control Function (S-CSCF); and the modifying circuit is configured to modify the message including the auxiliary information so that the first user identity is included in a P-Asserted-Identity header of the message.