>>> I've been looking into this as well.  My theory is that most
>>> of the automated calling services these days have about one
>>> second of silence

>> I don't think the delay is intentional or reliable...  If the
>> person receiving the call answers a little earlier than expected,
>> or the telemarketers take a little longer than expected to
>> complete the call, there is a short delay before a telemarketer
>> is available to have the call handed to.

> Or not. I find that, more often than not (I assume)
> there is no telemarketer available, so rather than pay
> the message units for a dead call they just drop the
> connection.

> This seems to knock out about 90% of those calls, although
> they do tend to call more often as a result.


There may be a way to build a device to not only block the
current telemarketing call but also reduce the future calls.
Let me tell you a little story...

A friend (new co-worker) of mine used to work for DEC.  The
group in which he worked provided the computer support for
the telemarketing arm of a large company.

He described to me how the system worked.  As previously
described, there was a large pool of sales people.  Calls
were placed by computer on a predicted availability basis.
Once the call was answered, the next available sales person
was connected to the victim.

But the telemarketer didn't want to waste sales person time
nor message unit money on unproductive target phone numbers.
So the computer system (which was placing calls) prescreened
for modem or facsimile machine tones.  If either was found,
the call was disconnected.  And the target number was marked
as non-voice to prevent future calls.

So I've thought a PIC device could be constructed to send out
a couple seconds of modem answer tone.  Or make the device more
sophisticated so it only does it if the box suspects the call
is a telephone solicitation.  Real people calling you would be
slightly confused and/or annoyed by the tones, but would
probably stay on the line.

I haven't tried to implement it (yet).
                                                Lee Jones