Martin McCormick wrote:
{Quote hidden}>
> 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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