DTMF vs. Pulse

Analog Connections - Address Signaling

• Dual-tone multifrequency (DTMF): The buttons on a telephone keypad use a pair of high and low electrical frequencies (thus "dual-tone") to generate a signal each time a caller presses a digit.
  
• Pulse: The rotary-dial wheel of a phone connects and disconnects the local loop circuit as it rotates around to signal specific digits.