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From: brian@ucsd.Edu (Brian Kantor)
Newsgroups: alt.folklore.urban,sci.electronics
Subject: Re: free calls?
Message-ID: <16832@ucsd.Edu>
Date: 5 Aug 90 17:49:56 GMT
References: <32457@cup.portal.com>
Followup-To: alt.folklore.urban
Distribution: na
Organization: The Avant-Garde of the Now, Ltd.
Lines: 30

The Electronic Serial Number of most cellular phones is contained in a
read-only memory chip inside the phone.  It is what identifies your
phone and distinguishes it from all the other yuppies on the service.

If the ESN were to be changed, one of the following would happen:

1) someone else would get billed for your calls

2) no one would get billed for your calls

3) you would not be able to make calls.

(1) would happen if your new ESN duplicated a registered user's number.
(2) would happen if the ESN landed on a demo or unassigned-but-authorized
    number
(3) would happen if the ESN was not authorized

#3 is probably most likely, but it depends on your local phone system.

In any case, you probably would not be able to receive incoming calls, since
the cellular system wouldn't know your phone's new ESN and couldn't map
your cell-phone number to it.

Most Cell-Phones have the ESN chip installed in a tamper-resistant
manner.  Sockets are rare - most are soldered in.  Nearly all are
covered with epoxy or some other goop that makes it hard to remove and
replace the chip without permanent damage to the phone.

Finally, it's illegal to avoid charges that way.
		- Brian