Transmitting information used to estimate a position of a mobile device. This disclosure describes NEAD-based and external location server (ELS)-based positioning systems and methods that determine when an identifier of a mobile device is not known or when the identifier of the mobile device is known but cannot be detected during a search by reference points, and to then provide a location of a reference point that had previous contact with the mobile device instead of an estimated position of the mobile device. The provided location of the reference point can be used by a location server to generate an estimate of mobile device position.