Patent ID: 8565186

Claim:
A method for registration and call setup of a mobile node in a visiting network, said method comprising the steps of: attaching a Session Initiation Protocol (SIP) registration message to a control message; transmitting said control message and attached SIP registration message from the mobile node to a first protocol component associated with the mobile node; simultaneously performing MIP registration using said control message and SIP authentication using said attached SIP registration message, said authentication comprising transmitting on a routing path without a home agent or foreign agent said attached SIP registration message from said first protocol component to a second protocol component, said routing path not traversing a home network of the home agent; and if said attached SIP registration message is authentic, transmitting via said routing path a reply to said attached SIP registration message to the mobile node, said reply having an IP address for said second protocol component, wherein said first protocol component is an application-specific relaying node.