Apparatus, and an associated method, for providing routing information to a mobile node operable in a radio communication system. The routing information is used by the mobile node to address data messages that are to be communicated to a relay host, or other, device. The routing information that is provided to the mobile node includes a plurality of separate routing sequences. Different ones of the routing sequences are used by the mobile node, depending upon at what location that the mobile node is positioned when the data message is sent. A registration server is used by which to create the routing information, responsive to indications of a home network associated with the mobile node and a current location of the mobile node.