On 2/13/2016 8:50 AM, Wade Garrett wrote:
On 2/12/16 8:21 AM, Don Y wrote:
On 2/12/2016 4:58 AM, philo wrote:

SNIP

In the early 80's, I was in a little town in Southern CO (Florence).
I called home (east coast) from a pay phone (as calling from the
home of the folks I was staying with would have passed the cost
onto them!). Of course, parents seem to like to talk for long
periods of time, saying little -- oblivious to the fact that I'm
standing on the side of the road calling from "nowhere".

Periodically, the operator would come on the line to tell me to
deposit another $3 (or so).

The first time I did this (to initiate the call), the solenoid that
transfers the monies from the "holding area" (from which they can
easily be RETURNED to the caller) to the "cash box" appeared to
malfunction; returning the coins to *me* instead!

pleasant surprise

Even more pleasant was that the next request for $3 resulted in the
same behavior. And, the one after that! (did I mention that parents
like to talk for a long time??) I just kept taking the coins out
of the coin return and redepositing them!

So, the call cost me nothing.

Next day, I drove by that same phone booth and, on a whim, tried
again. grin Same "problem" as the day before!

I did this for the better part of a week.

Until, one day, the activation of the solenoid resulted in the
coins being *accepted*. It was a very sad sound! :-(

Back in the day, there was a way to multi-bend a foot-long length of coat
hanger wire which could then be inserted up the open coin return slot of the
old Bell System pay phones-- the ones before they installed pull-down doors on
the coin returns-- that would lodge behind the holding box and prevent the
operator-activated solenoid from tipping it backward into the money box. A
skillful jiggle on the wire would tip the holding box forward sending the coins
back down the coin return slot. Free call!

The increasingly widespread use of these "pay phone hooks" back in the 50's and
60's was a contributing factor in Ma Bell's replacing all the old open-slot
coin return slot phones with the pull-down door kind...

There's also a spot on the "Fortress" where you can drill a little
hole and get similar results.

Ma Bell went to great lengths to protect the cash it had collected;
not so much *future* cash!

Coin mechanisms (and coin handling) suffer from being a relatively
complex task *and* one that you would ideally NOT like to spend
lots of resources ($$) on -- as it adds no direct value (it's
more of an insurance policy).

Early dollar bill validators could be hacked by attaching a length
of clear plastic to the bill (most typically, a long piece of tape
that is then folded back on itself to double its thickness/strength
*and* cover up the exposed adhesive soas not to get caught in the
mechanism).

The coin mechanisms in pin-tables (and other arcade pieces) can almost
always be conned into accepting a penny as "payment" (in lieu of a quarter).

Red boxes can con TPC into thinking you've inserted coins.

Some slot machines could be "confused" to miscount dispensed coins
(on a payout) by flashing a light *inside* the hopper (coin
dispenser) to blind the photoelectric "coin detector".

Etc. The number of vulnerabilities that folks will uncover
"to make/save/steal a buck" is amusingly large: "Why didn't
anyone think of PREVENTING this *obvious* hack?"