Product Description

• Dual-tone multi-frequency signaling (DTMF) is used for telecommunication signaling over analog telephone lines 
  in the voice-frequency band between telephone handsets and other communications devices and the switching center.
• The version of DTMF that is used in push- telephones for tone dialing is known as Touch-Tone. This dtmf shield

  provides the same interface of touch tones to be controlled with any open source microcontroller.
• One of the easiest methods of automated radio control makes use of Dual-Tone Multi-Frequency signalling.