Dual-tone multi-frequency signaling (DTMF) is an in-band telecommunication signaling system using the voice-frequency band over telephone lines between telephone equipment and other communications devices and switching centers. DTMF was first developed in the Bell System in the United States, and became known under the trademark Touch-Tone for use in push-button telephones supplied to telephone customers, starting in 1963.DTMF is standardized as ITU-T Recommendation Q.23.It is also known in the UK as MF4.

 

Specifications:

• Onboard Complex Frequency Decoder IC 8870
• On board 5LED indicators for easy viewing output state
• DC Power Supply Voltage : 5V (4.5V-5.5V)
• Operating Temperature : -40-+85 °C
• IO Drive : Current Maximum 10 mA.
• PCB Size: 55.9 (mm) x 43.1 (mm)