[VoIP] [originally from Strowger] A NYC Payphone Puzzle

[Steph Kerman]

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