One late night many decades ago, I chanced upon a technical description of the Touch-Tone system. The book I was reading had an explanation of how each key on a telephone sends a combination of two ...

DTMF (Dual Tone Multi Frequency) is a signaling system for identifying the keys or better say the number dialed on a pushbutton or DTMF keypad. DTMF (Dual Tone Multi Frequency) is a signaling system ...

Excellent to remotely control via GSM the activation of engines, lightening or watering systems and alarm systems. It sends commands through SMS as well as with DTMF dual tones and allows you to check ...

Just got a new Galaxy S5. So far I'm loving the phone, with one fairly major annoyance - what the hell were they thinking when they used some bubble sound for the keypad tones? Is there any way to get ...