Path: utzoo!attcan!uunet!cs.utexas.edu!mailrus!accuvax.nwu.edu!nucsrl!telecom-request
From: covert@covert.enet.dec.com (John R. Covert  09-Jun-1990 1015)
Newsgroups: comp.dcom.telecom
Subject: Re: Two Cellular Phones, Same Number
Message-ID: <8827@accuvax.nwu.edu>
Date: 9 Jun 90 14:25:33 GMT
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X-Telecom-Digest: Volume 10, Issue 424, Message 2 of 5


>A friend of mine wants to have two cellular telephones in two
>different cars with the same telephone number.  Of course, he will use
>only one at a time.  The telco won't set this up for him.

This really isn't technically possible.  Even if he promises to never
turn power on to both of them at the same time, accidents do happen.
If power were on to both units at the same time, both units would
respond to commands from the cells, and bad things would happen, which
would generate trouble reports and possibly disturb other calls in the
system due to co-channel interference.

Although a single ESN may have an infinite number of telephone
numbers, each telephone number can have at most one ESN.  This is an
immutable part of the design of the AMPS system.  Although the
moderator suggests that the way around this would be to convince the
cellular carrier to not do its usual serial number check as part of
handling his calls, this has all the problems mentioned above, plus
the problem of making the roamer validation system not work.  Mr.
Cantor would be subject to fraud from anyone anywhere in the U.S. or
Canada who knew that his phone number had no ESN.

The only option is to have a portable which is carried from car to
car.  Some portables, especially NEC and Motorola portables, are
designed such that you can install a complete set of 3 watt
electronics in each car which are activated only when the portable,
which contains the number and ESN, are plugged into the socket in the
car.

This way, someone who drives two cars can have a single phone number
for each car.  Or, better yet, two people who share two cars can each
have their own portable and their own number will always be active in
the car they are driving.


/john

[Moderator's Note: Actually, Mr. Covert's suggestion, re use of
portables, makes a lot of sense. There are so many varieties now, and
the price has come down so much, it seems far more efficient to simply
transfer a hand-held unit from one vehicle to another ... and carry it
when you leave the vehicle, as I do. A couple portable units, combined
with call-forwarding as needed should be adequate.  PT]