In a radio telephone system and a call charging method used in the radio telephone system, when a user of a radio telephone issues a telephone call to a public telephone network by utilizing a radio controller installed in a PBX employed on the premises of a company to which the telephone user does not...http://www.google.de/patents/US5425083?utm_source=gb-gplus-sharePatent US5425083 - Call charging method in radio telephone system and radio telephone system employing the same method
