Patent ID: 8346720

Claim:
An information update system comprising: a plurality of application server apparatuses to serve a subscriber with respective application services through a corresponding SIP (session initiation protocol) server; and a home subscriber server apparatus to store information regarding the subscriber and connected to the application server apparatus and to the SIP server, wherein each of the plurality of application server apparatuses comprises a transmitting unit to transmit an update request signal to the home subscriber server apparatus for requesting updating of the information regarding the subscriber, the update request signal including update contents, and the home subscriber server apparatus comprises: a selector configured to select, when receiving the update request signal, an updating method corresponding to said update request signal from a plurality of updating methods; and an updating unit to update the information regarding the subscriber in accordance with the update contents contained in the update request signal through the selected updating method, wherein each of the plurality of application server apparatuses adds an identifier for identifying an updating method to the update request signal to be transmitted to the home subscriber server apparatus, and the selector selects the updating method identified by the identifier added to the update request signal out of the plurality of updating methods, and further wherein the updating method is one of a first win scheme and a last win scheme, the information is updated based on an update request signal received first by the home subscriber server when the first win scheme is selected by the selector, and the information is updated based on an update request signal received last by the home subscriber server when the last win scheme is selected by the selector, wherein the plurality of updating methods include: a first updating method in which information is updated based on an update request signal received by the home subscriber server apparatus, if the update request signal has a same sequence number as a current sequence number which is currently stored in the home subscriber server apparatus and changed every time the home subscriber server apparatus updates information; and a second updating method in which information is updated based on every update request signal which is received by the home subscriber server apparatus.