Description:

This application listens for fax tones (on IAX and SIP channels
too) for waitdur seconds of time. In addition, it can be
interrupted by digits, or non-silence. Audio is only monitored in
the receive direction. If digits interrupt, they must be the start
of a valid extension unless the option is included to ignore. If
fax is detected, it will jump to the 'fax' extension. If a period
of non-silence greater than 'mindur' ms, yet less than 'maxdur' ms
is followed by silence at least 'sildur' ms then the app is
aborted and jumps to the 'talk' extension. If all undetected,
control will continue at the next priority.