‘Touch-Tone’ remained a registered trademark of Bell Systems, and later AT&T, until 1984. Over the following decades, it gradually replaced the earlier Pulse Dialing or Rotary Dialing technology. DTMF was invented by the Bell Telephone Company in 1963. Dual Tone Multi-Frequency is a signal tone generated when buttons are pushed on a telephone keypad – hence the term ‘Touchtone Phone’.
0 Comments
Leave a Reply. |