Abstract: A system for providing a bi-directional communication service is provided. The system includes a client terminal and a bi-directional communication service providing/managing server. The client terminal sends a short message after passing a user authentication and receives a short message from outside. The bi-directional communication service providing/managing server transmits the short message sent by the client terminal simultaneously to at least two other party client terminals after a user authentication process, or transmits a short message received from another party client terminal to the client terminal after a user authentication process.

Abstract: A method of supporting a mobile station that is in an idle mode in a wireless communication system using a paging controller comprises entering an idle mode by a mobile station, receiving a paging command from a base station in the same paging group, the paging command comprising a paging command action code associated with performing ranging while the mobile station is in the idle mode to verify availability of the mobile station with respect to at least one of the base stations in the paging group, wherein the paging command is generated from the base station in response to a paging announcement from the paging controller, and exiting the idle mode and establishing communication with one of the plurality of base stations, wherein the plurality of base stations in the same paging group receive an idle mode exist status from the paging controller.

Abstract: A method of entering sleep mode in a mobile subscriber station in performing handover from a first base station (BS) to a second BS is disclosed. More specifically, the method includes entering sleep mode in the first base station and transmitting from the first base station sleep mode information in the first base station during handover, while receiving from a second base station sleep mode entry information in the second base station. The method further includes entering sleep mode based on the information the sleep mode entry information received from the second base station.