A user maintains notification setting information having temporal periods capable of controlling, at least in part, the dissemination of information describing the on-line presence of the user within an instant messaging system or the geographic location of one or more mobile communications devices used by the user. The user may use multiple identities to communicate within the instant messaging system and/or with the mobile communications device or devices. The user can maintain sets of temporal periods for each of the multiple identities. Only one identity may be used at a specific time to communicate to a specific other identity, but the multiple identities of the user may be linked such that on-line presence and/or geographic location associated with one of the identities is disseminated based on the temporal periods set for one or more of the multiple identities.