Coin charging system for mobile telephony in order to facilitate the making of telephone calls by means of a mobile telephone with a coin charging system, mainly in public transport means such as buses, airplanes, trains, ships etc., the system being provided with normal operation modes as ...http://www.google.fr/patents/US5809124?utm_source=gb-gplus-shareBrevet US5809124 - Coin charging system for mobile telephony
