Multifrequency pulsing in switching

The Democratization of Artificial Intelligence

“…This so-called dual-tone multi-frequency (DTMF) dialing method was based on a four-by-four frequency scheme proposed by L. A. Meacham of Bell's Station Development Department, although initially only seven frequencies (four in the low end of the spectrum and three in the higher range of the spectrum) would generate ten unique pairs of tones (Meacham et al 1958). 3 The method made use of state-of-the-art solid-state technology and was grounded in a number of field trials conducted between 1948 and 1960 (Dahlbom et al 1949;Hopkins 1960). When dialing a number, the dual-tones provided a helpful acoustic feedback for the caller.…”

The Democratization of Artificial Intelligence

“…This so-called dual-tone multi-frequency (DTMF) dialing method was based on a four-by-four frequency scheme proposed by L. A. Meacham of Bell's Station Development Department, although initially only seven frequencies (four in the low end of the spectrum and three in the higher range of the spectrum) would generate ten unique pairs of tones (Meacham et al 1958). 3 The method made use of state-of-the-art solid-state technology and was grounded in a number of field trials conducted between 1948 and 1960 (Dahlbom et al 1949;Hopkins 1960). When dialing a number, the dual-tones provided a helpful acoustic feedback for the caller.…”