[VoIP] [Strowger] Re: [originally from Strowger] A NYC PayphonePuzzle

Tue Oct 10 05:11:48 CDT 2006

Hi,
Sorry I'm not on all six of these lists, just Voip and Centraloffice.
Anyway, a few years ago I was reading some red boxing articles on maybe
Phonelosers? where they talked about some coin line phones having
mouthpieces which either weren't on until coin deposit, had filters to
prevent those tones from going through, etc. in order to defeat red boxers.
Of course if you're talking to an operator who's asking for money you have
to be able to talk to her and deposit *real* coins, so the mouthpiece can't
be disabled during this time.
Jayson.

----- Original Message ----- 
From: "Steph Kerman" <stfkerman at jps.net>
To: <Strowger at yahoogroups.com>; "ATCA" <ATCA at LISTSERV.ICORS.ORG>;
"ATCA-Yahoo Group" <atcaclub at yahoogroups.com>; "TCI"
<singingwires at yahoogroups.com>; "Central Office"
<centraloffice at yahoogroups.com>; "VoIP" <voip at ckts.info>
Sent: Monday, October 09, 2006 3:49 PM
Subject: Re: [VoIP] [Strowger] Re: [originally from Strowger] A NYC
PayphonePuzzle

> Hi Bernard,
>
> In a digital office, the tone would have to be within the passband of
> the anti-aliasing filter of the subscriber line codec.  I'd guess that
> the transmitter has a wider passband than the filter, which cuts off
> quite abruptly around 3KHz.  In Automated Coin Telephone Service, toll
> deposits are detected at the TSPS tandem office.  Therefore the coin
> deposit tones would need to be detectable over a 3KHz T1 channel.
>
> I do believe that the first coin deposit changes a DC condition in the
> telephone that can be interrogated by the COE.  So the COE can determine
> whether one or more coins or the "initial rate" is actually in the
> hopper.  AFAIK, to use a red box successfully, one should deposit one
> nickel or perhaps the inital rate first and then use the red box for the
> remaining deposits.  This way, if the COE performs an intial rate or
> coin presence check before call completion, it will succeed.
>
> Steph
>
> Bernard Green wrote:
> > Steph
> >
> > I cannot recall from where I heard this but I do recall an attempt to
beat the red box hacking  by using a tone that was outside the working
frequency range of the microphone.
> >
> > The use of an intelligent ( but not vandal proof  ) phone for pay phones
would remove the need to have fee checking on allocated lines in the
exchange.
> >
> > Regards
> >
> > Bernard Green
> > Dead ringer for a Wanna bee telephone engineer
> >
> >
> >
> >
> > ----- Original Message ----- 
> >   From: Steph Kerman
> >   To: ATCA ; ATCA-Yahoo Group ; TCI ; Central Office ; VoIP ; Strowger
List
> >   Sent: Monday, October 09, 2006 8:20 PM
> >   Subject: [Strowger] Re: [originally from Strowger] A NYC Payphone
Puzzle
> >
> >
> >   Interesting thoughts, Bernard.
> >
> >   The majority of Telco owned payphones in the US are connected to "coin
> >   lines".  Privately owned payphones use ordinary lines with
intelligence
> >   inside the payphone and would be vulnerable to the "hack" you
described.
> >
> >   On coin lines, there would be no extra benefits from having metallic
> >   access to the line since the COE rates the call and supervises for
coin
> >   deposits.  The transmitter is enabled from the moment dial tone is
> >   received, so arbitrary tones can be sent by acoustic coupling without
> >   metallic connection.  Indeed, the "red box" does precisely this,
> >   emulating coin deposit tones.
> >   It would probably be much easier to get access to the line by opening
> >   the base of the pedestal, which I think is assembled with "security"
> >   Allen screws having a center post, requiring a hollow Allen driver.
> >
> >   Although 2 dial leads are visible hanging out from the front opening,
> >   I'm pretty sure even a modernized dial implementation has at least 3
> >   leads.  But probably it has 5 or more leads since traditionally, the
> >   receiver was muted first by separate contacts to prevent audible
clicks,
> >   the transmitter was then disabled and the line was then switched to
the
> >   oscillator last.
> >
> >   However it is interesting that they pulled these two leads out through
> >   the front holes.  That may indeed be a clue.  I'll have to try out
that
> >   phone and see whether it is a dumb phone on a coin line or a smart
phone
> >   on an ordinary line.  I am not aware of Verizon using smart phones
> >   within their own service area.
> >
> >   Steph
> >
> >   Bernard Green wrote:
> >   > First thing that comes to mind is that having gained access to the
wires to the touch tone keypad a more versatile tone generator could be
connected. This may provide " extra benefits" to the vandal in routing
calls.
> >   >
> >   > Maybe the two wires to the keypad would allow an ordinary phone to
be connected to the line and thus bypass the coin operated switches
> >   >
> >   > On UK coin boxes where the microphone was shorted until coins had
been inserted "vandals" would slit the sheath of the cable ( coin box to
phone ) and snip the brown wire to prevent the short being applied.
> >   >
> >   > Bernard Green
> >
> >
> >
> >
> >   Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
> >
> >
> >
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