Panasonic DF-1100 Service Manual page 223

DTMF Tone Generator
The circuit is incorporated in the MODEM on the FCB PC Board. The DTMF tone is conveyed to the
telephone line using the same route as the facsimile signal. The DTMF tone selection is controlled by the
CPU. The relay status during dialing is shown below.
DTMF Tone
break
PLS Relay
make
Q7 break
break
CML Relay
make
Speech
condition
Line release
Prepause
break
Line status
make
First Speech Second
digit condition digit
Inter-digit
pause
System Description
Speech
condition
DTMF signal
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