A telephone accessory communications device suitable for the delivery of DTMF tones over a standard telephone line, which has a card reader, microprocessor and telephone signaling generator that produces the DTMF tones corresponding to data encoded on the strip of a card. A memory device may also be...http://www.google.de/patents/US6535588?utm_source=gb-gplus-sharePatent US6535588 - Telephone accessory communications device
