pbx ~ # fxotune
Usage: fxotune [-v[vv] (-s | -i <options> | -d <options>)

        -s : set priviously calibrated echo settings
        -i : calibrate echo settings
                options : [<dialstring>] [-t <calibtype>]
                [-b <startdev>][-e <stopdev>]
                [-n <dialstring>][-l <delaytosilence>][-m <silencegoodfor>]
        -d : dump input and output waveforms to ./fxotune_dump.vals
                options : [-b <device>][-w <waveform>]
                   [-n <dialstring>][-l <delaytosilence>][-m <silencegoodfor>]
        -v : more output (-vv, -vvv also)

                <calibtype>      - type of calibration
                                   (default 2, old method 1)
                <startdev>
                <stopdev>        - defines a range of devices to test
                                   (default: 1-252)
                <dialstring>     - string to dial to clear the line
                                   (default 5)
                <delaytosilence> - seconds to wait for line to clear (default 0)

                <silencegoodfor> - seconds before line will no longer be clear
                                   (default 18)
                <device>         - the device to perform waveform dump on
                                   (default 1)
                <waveform>       - -1 for multitone waveform, or frequency of
                                   single tone (default -1)