In a group list update method, a group data server signals to one or more registration servers (e.g., a SIP registration server and/or a Mobile-IP registration server), to notify the registration servers of a group list update. In turn, the next time the registration server sends a registration response to an affected wireless client station, the registration server will include in the registration response a flag indicating that an update is available (or, e.g., an indication of the current version of the group data). In response to being alerted of that updated group data is available, the recipient wireless user station will then send an update request to the group data server, and the group data server responds by conveying the group list revisions to the user station.