The invention relates to a self-locking nut having an upper threaded collar provided with longitudinal slots, being V or U shaped, also with sharp edge, defining in the collar a plurality of circular arc segments compressed by an external helical spring, and in which the collar slots have such a width as not to allow the mutual contact of the circular arc segments compressed by the spring. A sending terminal transmits to a user interface information concerning the data of sound such as voice and digital sound, destination information and date information. The second route search server searches for an optimal route which satisfies a route search condition.