Method for using recording rules and previous value selection rules for presence information in a communications system

摘要

In a communications system, a presence server maintains and distributes presence information in accordance with recording rules and previous value selection rules. The presence server: associates (202) a recording rule with each presence information element in a subset of a plurality of presence information elements for a presentity; maintains (204) a set of previous values according to the recording rule associated with the presence information element, for each presence information element in the subset; receives (206) an initial subscribe request from a watcher for one or more presence information elements in the subset; and in response to the initial subscribe request, notifies (208) the watcher of a number of the previous values maintained for each presence information elements in the subscribe request, wherein the number of the previous values that is sent is determined by a previous value selection rule associated with each presence information element.