DTMF (Dual-tone multi-frequency) tones are the sounds generated by touch tone phones. 
When a key on a phone keypad is pushed not one but two different frequencies are 
generated, hence the name dual tone multi frequency. 

DTMF 1 = 697 Hz & 1209 Hz
DTMF 2 = 697 Hz & 1336 Hz
DTMF 3 = 697 Hz & 1477 Hz
DTMF 4 = 770 Hz & 1209 Hz
DTMF 5 = 770 Hz & 1336 Hz
DTMF 6 = 770 Hz & 1477 Hz
DTMF 7 = 852 Hz & 1209 Hz
DTMF 8 = 852 Hz & 1336 Hz
DTMF 9 = 852 Hz & 1477 Hz
DTMF 0 = 941 Hz & 1336 Hz

DTMF * = 941 Hz & 1209 Hz
DTMF # = 941 Hz & 1477 Hz
DTMF busy signal = 480 Hz & 620 Hz
DTMF dial tone = 350 Hz & 440 Hz
DTMF ringback tone (US) = 440 Hz & 480 Hz


True 2600 hz Tone


Of course we can drive by smell b1tches...