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Call Progress Tone Processor Disclosure Number: IPCOM000039359D
Original Publication Date: 1987-May-01
Included in the Prior Art Database: 2005-Feb-01

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Toma, SK Whitlock, LW [+details]


A simple, inexpensive, reliable circuit means is described for decoding U.S. call progress telephony tones, specifically dial, busy and ringback. Today there is an emphasis in the telecommunications industry on merging the communication capability of the public switched network with the digital computer. A key requirement is the ability to process call progress tones signalled to the telephone. In the U. S., these tones are specified in the EIA RS-464 standard.