Martin McCormick wrote:
>
> Mark Willis writes:
> >Do you mean the triple tone that you get when you dial a number that
> >doesn't exist (3 tones, each higher in pitch than the last)?
>
>         I am sure that is what he is referring to.
>
>         I have also heard that those call directors that telemarketers
> use look for a single burst of audio when the line is answered such as
> "hello" or something else short to know that they've got a live one.
> If they get a bunch of audio, they know they've got an answering
> machine and  they hang up.
>
>         I put an old cast-off answering machine on our modem line at
> home and put a message on the tape that starts with "Hello," then
> pauses for about 5 seconds before telling the caller that he/she/it
> has the wrong number.
>
>         We used to get about one or two calls per week on that number
> from telemarketing dweebs, but the calls have dropped to virtually
> zero after a couple of years of this.  When playing the answer tape
> back, I have been amused to sometimes hear an obvious telephone boiler
> room operation chattering away in the background and a frustrated
> expulsion of breath by someone who has probably gotten that "dead
> line" again which is wasting their precious time.  I imagine that by
> the time the call director has routed to one of the teledweebs, my
> message explaining about the wrong number has already passed so the
> telemarketer just hears dead air.  Funny, they don't like it any more
> than I do.
>
>         Ah, the simple pleasures of life;  the song of a bird, the
> smell of fresh air on a chilly evening and the sound of a ticked-off
> telephone salesman.
>
>         To keep it mildly close to PIC's, I think a PIC could produce
> those SIT tones with no trouble, but I am not sure if they are meant
> to automatically signal a bad line or if they are just there to tell
> us we've goofed.
>
> Martin McCormick

The "You misdialed" tones are sure loud enough around here, enough to
crack an eardrum...

If you wanted a PIC to produce those, you might want to PWM them, using
"magic sines", then RC filter the result to give a clean sine-ish wave
form.  Square waves are SO nice in higher odd harmonics <G>  Probably
could just low-pass filter them, if the tones are right (and, the phone
line probably helps roll off the upper frequencies <G>)

James - saw your post;  Good info - Thanks!  This'd make a good 12C508A
project, I'm out of small cheap speakers though, for testing, darnit
<G>  (Used to be able to get one for under a buck, now everyone wants $%
or so?!?)  That'd be great to put on my BBS and FAX lines here.  Would
want a good telephone interface design/IC, of course, in there <G>

  Mark

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