A mobility event for a VoIP user is detected, with an estimated confidence/certainty that the VoIP user in fact moved. In response, a user is prompted to cause an update to their registration and/or location information. Notification to the VoIP user of the likely need for a location update may be implemented in the communication protocol such that an icon on the VoIP phone displays the need to the VoIP user. The icon may include a measure of the confidence/certainty of the need for a location update, e.g., similar in visual image to the bars showing coverage on a wireless phone. Mobility of the VoIP user may be detected using, e.g., (1) The VoIP user's Internet protocol (IP) address; (2) a mapping of physical to logical location; and/or (3) mapping between physical location information and physical network resources such as switches, routers, ports, access points, etc.