Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!kitty!larry
From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: sci.electronics
Subject: Re: How to Hack Payphones (?!)
Summary: More on coin telephone operation...
Keywords: hack, payphone
Message-ID: <3218@kitty.UUCP>
Date: 10 Jun 89 14:17:13 GMT
References: <3685@tank.uchicago.edu> <2803@portia.Stanford.EDU>
Distribution: usa
Organization: Recognition Research Corp., Clarence, NY
Lines: 46

In article <2803@portia.Stanford.EDU>, mesmo@portia.Stanford.EDU (Chris Johnson) writes:
> 	Another interesting phone mini-hack: back in high school,
> 	our pay phone could be dialed for free by rapidly clicking
> 	the hang-up toggle in the pulse-pattern of the number you
> 	wished to dial.

	This would only work in older multi-slot coin telephones arranged for
for pre-pay service.  Depositing a coin places a ground on the telephone 
pair (balanced between tip and ring), in addition to removing a short
bridged across the dial pulsing contacts, therefore enabling the dial.

	Since a pre-pay coin telephone line is similar to a ground-start
line, momemtarily grounding the line by piercing the handset cord or
transmitter with a sharp object connected to the telephone housing will
result in dial tone without the use of a coin.  Since the dial is disabled
without a coin, rapid switchhook operation can be used to create dialing
pulses.

	While the above method of operation is also true for 1A-type and
1C-type single-slot coin telephones arranged for pre-pay operation, I
do not believe it is possible to "pulse-dial" the switchhook on these
style coin telephones due to its different mechanical design (obviously
intentional!).

> 	Interesting & cheap, too.  Haven't tried this in a while,

	Since this method of fraud only applies to pre-pay coin telephones,
which are becoming almost non-existant in most areas of the country, it
isn't going to work on very many telephones.

> 	any ideas why pulse-dialing isn't disabled from touch tone
> 	payphones (at least that one) ?

	While it is possible to block rotary dialing in some ESS central
office apparatus, there really is no need to do so with dial tone first (DTF)
coin telephone service since the telephone user IS ALWAYS permitted to dial
the initial call.

> 	p.s. the phone company is your friend

	That's a debatable statement. :-)

<>  Larry Lippman @ Recognition Research Corp. - Uniquex Corp. - Viatran Corp.
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