Patent ID: 8041398

Claim:
A method for achieving a presence service in a communication network, comprising: providing a presence server that is configured to wait for arrival of an update message from a device; the presence server receiving the update message; the presence server checking the update message to determine if the update message signals a change in state of a user or a device associated with the user; the presence server determining whether an entry exists for the user or the device associated with the user in at least one buddy list if the presence server determines that the update message signals the change in state of the user or the device associated with the user, if no entry in the at least one buddy list exists for the user or the device associated with the user in the at least one buddy list, the presence server awaiting for another update message; if an entry exists for the user or the device associated with the user in the at least one buddy list, the presence server determining whether the at least one buddy list is in a deactivated state or an activated state, if the at least one buddy list is in the deactivated state, the presence server suppressing sending of any buddy list update message to the at least one buddy list, the buddy list update message configured to identify the change in state of the user or the device associated with the user such that the buddy list update message is not transmitted to the at least one buddy list and storing the change in state and after a predetermined time has elapsed the presence server sending a group message to the at least one buddy list that identifies states of all users of the at least one buddy list and all devices associated with those users of the at least one buddy list; and if the at least one buddy list is in the activated state, the presence server sending at least one buddy list update message such that the change in state is indicated on a display device of a terminal device via the at least one buddy list without waiting for the predetermined time to elapse; and wherein at least one buddy list is in the deactivated state and the at least one buddy list in the deactivated state is also updated if a change in any non-realtime-critical states of the user or the device associated with the user is detected by the presence server via the update message without waiting for the predetermined time to elapse; and wherein the at least one buddy list is configured to display realtime-critical state information of the user or device associated with the user and non-realtime-critical state information of the user or device associated with the user; and wherein for the at least one buddy list in the deactivated state, the at least one buddy list in the deactivated state is updated via the group message only for changes in non-realtime-critical states of the users or devices associated with those users of the at least one buddy list.