
The sound ID of telemarketers - ashitlerferad
http://zaitcev.livejournal.com/235580.html
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zzleeper
Can we use this to auto-block them? More generally, can we use data about the
call to do some spam filtering?

EG: listen to the first sec of a call and try to measure the amount of noise,
the amount of lag, or if there is any feedback at all (like you would have if
you were speaking with another human and not with a robot). Then use that to
either kill the call or make it sound.

~~~
daurnimator
But it's only after answering the sound happens. To filter based on it you'd
have to answer calls before the end user's phone even rung.

~~~
Turing_Machine
That doesn't seem to be all that difficult, conceptually.

Have the system pick up the call (without generating an audible ring for the
user) and listen for the block. If it hears it, buh-bye. If it doesn't hear
it, _then_ ring the phone for the user, while also playing back a simulated
"ringing" signal to the caller, so the caller was unaware that the call had
actually been "answered" already.

~~~
Splines
Conceptually simple, but "answering" the phone with a simulated ring has a lot
of side effects. For example, voice mail might be broken.

I'm unfamiliar with the exact specifics of how phone calls are routed, but you
might be able to get away with more if you own the phone switch (e.g., self-
hosted asterisk or something like that).

~~~
r00fus
I have to be that guy to ask: Does anyone use voicemail anymore? My family
doesn't even now that they all have smartphones. No answer? Followup SMS with
basic question. Done.

~~~
ashitlerferad
Followup MMS is the best voicemail method.

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eyeJam
i've noticed when i'm called by telemarketers that it's dead silent when i
answer. no background noise, no static, just the click that this guy is
talking about. if i don't say anything or make any noise and wait for them to
say hello first, the autodialer disconnects the call after a couple seconds.

~~~
randycupertino
This is because the autodialer won't assign an agent to your call unless it
detects you picking up and speaking. At least, that is how it worked at my old
call center, thank the lords I don't work there any more.

The bulk dialer would dial hundreds of numbers per minute, but we would only
have 5-10 agents per shift sitting in the queue for outbound calls (most hated
shift at the call center), so not worth it to have them all sitting there on
the line while it's ringing.

That time period where it's dead air is the autodialer routing your call to an
agent.

Same reason you get halfway through or cutoff voicemails from robocalls...
they can't tell the difference between a voicemail and you talking so the
robomessage starts playing before the voicemail takes the message.

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flashman
Would be good to get a recording of it.

If I had to guess, I'd say it's something to do with adding a salesperson to
the call. Imagine your agents are sitting there manually making calls and
waiting for a pickup (preview dialling). That's time they could spend talking.
Some outbound call systems will make multiple calls at once, then hand over to
human operators once a connection is established on any of them (progressive
or predictive dialling).

The tone might be played as part of handing over a predictive call to an
agent.

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kimi
"It is also customary to send a background tone (be it blank or a beep) to the
called party to help set-up the line on SIP circuits. This way the accuracy of
AMD is reported to be increased considerably."

Source: [http://manuals.loway.ch/WD_UserManual-
chunked/ch03.html#AMDF...](http://manuals.loway.ch/WD_UserManual-
chunked/ch03.html#AMDFAX)

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bryanhun
Might be related to AMD (Answering machine detection)?

[https://support.twilio.com/hc/en-
us/articles/223132567-Can-T...](https://support.twilio.com/hc/en-
us/articles/223132567-Can-Twilio-tell-whether-a-call-was-answered-by-a-human-
or-machine-)

~~~
viraptor
It works the other way. AMD waits for a response normally, but doesn't play
anything. Maybe there's some special case they're trying to trigger, but it's
not the "usual" AMD.

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gergles
Caller ID being played in-band for some reason? That's about the right amount
of time and what it sounds like.

