Abstract: A navigation guidance system is provided which provides direction information from a remote server to a mobile user unit for guiding user to a desired destination. The navigation guidance system maintains time-related models for traffic speeds expected on road segments of a road database. By maintaining such time-related models, the system can more accurately provide the user with road guidance instructions to arrive at a chosen destination by a given time. The system can also provide more accurate route guidance information to a destination over different routes, even during rush hour or at off peak times. These time related models can be changed as a result of changing traffic patterns or as a result of an incident on a road segment. In a preferred embodiment, therefore, the system continuously monitors each calculated route and advise the users of alternative routes or of updated departure or arrival times as appropriate.

Abstract: A navigation guidance system is provided which gives direction information from a remote server to a mobile user unit for guiding the user from their current location. The user unit may be a mobile telephone, PDA or the like. A navigation query is transmitted from the user to the remote server. A GPS receiver or the like is provided so that the current location of the mobile unit can also be determined and provided to the remote server. Based on the information received from the user, the server determines appropriate route guidance information and sends this back to the user. In a preferred form of the invention, the data is transmitted between the user unit and the remote server using DTMF tones which are encoded so that no two consecutive tones are identical.