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MT8880 to detect busy and connection estalishment


Nico Coesel

Jan 1, 1970

I used MT8880 to dial a call. But I do not know how to detect busy and
connection estalishment?

Some of these chips (which can also receive DTMF) have a call progress
mode. In this mode the call progress tones are filtered and presented
as a digital signal on a output. If you send this signal through an RC
filter, you can use a microcontroller to detect the rithm of the
signal and determine which tone you are receiving. Bare in mind that
it takes several seconds to determine the signal.