Patent ID: 8358649

Claim:
A system accompanying with a first subscriber identity card and a second subscriber identity card for handling packet-switched data transmission, wherein the first subscriber identity card camps on a cell via a first RF module and the second subscriber identity card camps on the same cell or a different cell via a second RF module, comprising: a load balancing unit receiving an uplink IP packet, determining one subscriber identity card from the first and second subscriber identity cards when the uplink IP packet comprises information regarding an unestablished connection of a recognized application, determining a default subscriber identity card from the first and second subscriber identity cards when all port numbers present in the uplink IP packet are not recognized, determining one subscriber identity card previously utilized when detecting that a former IP packet comprising the same connection as that of the uplink IP packet, and transmitting the uplink IP packet to a destination via the determined subscriber identity card and the RF module corresponding to the determined subscriber identity card, wherein the application corresponds to a port number, and the connection is a combination of a source address, a destination address, a source port number and a destination port number of the uplink IP packet.