Newsgroups: sci.electronics
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: How can I restrict outgoing phone calls?
Message-ID: <1989May18.042535.9003@utzoo.uucp>
Organization: U of Toronto Zoology
References: <778@tetons.UUCP> <21001@genrad.UUCP>
Date: Thu, 18 May 89 04:25:35 GMT

In article <21001@genrad.UUCP> cah@genrad.UUCP (Chris A. Heitmann) writes:
>...If you do what you say, disable the keypad, they
>can still make calls anywhere they want with a hand held dialer (assuming
>that you have tone service)...

And if they're deft, they can make calls anywhere they want even if you
*don't* have tone service, by rapidly pulsing the hookswitch (the switch
that distinguishes between "on hook" and "off hook", often by having the
receiver's weight rest on it when "on hook").  All a conventional phone
dial does as it returns after you've turned it to a number is to open
and close the circuit repeatedly.  Phone exchanges are tolerant enough
that you can do the same thing manually, at least on a standard Bell
phone.  (Might not work on electronic ones.)
-- 
Subversion, n:  a superset     |     Henry Spencer at U of Toronto Zoology
of a subset.    --J.J. Horning | uunet!attcan!utzoo!henry henry@zoo.toronto.edu