Abstract: A Short Message Service (SMS) message is communicated to a mobile user equipment (MUE) over an Internet Protocol (IP) network using an IP communication. An SMS network includes a Short Message Service Centre (SM-SC), a gateway mobile switching centre (GMSC), the SMS network communicating SMS messages. An IP/SMS gateway communicates between the SMS and IP networks. A home location database maintains address data identifying a current location of a MUE. After interrogation by the GMSC, the home location database provides the GMSC an address of the IP/SMS gateway, stored in association with the subscriber identify number. The GMSC sends the SMS message to the IP/SMS gateway. The IP/SMS gateway retrieves an IP address corresponding to the mobile subscriber number pre-stored in an IP/SMS database associated with the IP/SMS gateway. The IP/SMS gateway communicates the SMS message to the MUE at the retrieved IP address via the IP network.

Abstract: Apparatus for and methods of enabling a gateway node of a first packet-switched data network to select a first channel for transferring a data packet to a destination packet data protocol address of a correspondent node provided service in the first network are disclosed. The gateway node is configured to select the first channel from a plurality of channels configured to transfer data packets to the destination packet data protocol address of the correspondent node, wherein the data packet is sent from a mobile node of a second packet-switched data network external to the first network, and wherein the mobile node has been in a communication session with the correspondent node while provided service in a third packet-switched data network different to the second network.