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==Phrack Inc.==
Volume One, Issue Six, Phile 7 of 13
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Cellular Telephones
[Written By The High Evolutionary]
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I assume that most of us know many of the technical aspects of Cellular
Phreaking therefore this file is intended for general information as to how
these unique devices operate.
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Cellular is likely to be successful because it provides dramatic
improvements over the historic automobile phones. For years, mobile
radio-telephone service was an extremely limited proposition. There were only
forty-four radio channels available, and a maximum of about thirty were
assigned to any one area. That meant if all thirty channels were occupied-one
conversation per channel-and you were the thirty-first mobile phone user who
wished to make a call, you would have to wait thirty minutes or more, even in a
city the size of New York. As you can imagine, mobile radio-telephone service
like that could not become very popular. Even with the limited number of
channels, long delays in making calls during busy periods, and often poor
quality transmission, there were big waiting lists for mobile service. But
with a fully equipped cellular radio-telephone system, it is possible to make
5000 times as many calls simultaneously in the same metropolitan area, opening
up the service to anyone that can pay the hefty prices.
That is because cellular radio-telephones systems are technically quite
different from traditional mobile telephones. First, the FCC (Federal
Communications Commission) has allocated far more channels to cellular, 666 in
all. Second, those 666 channels are broadcast from many different locations.
In the old mobile telephone systems, there was one powerful radio station with
a large antenna that served an entire city. In the new system, a geographical
area is honeycombed with many cells, hence the name 'Cellular'. Each cell has
its own low-powered radio transmitter and receiver. As a car with a cellular
telephone or a person carrying a portable moves from one cell to the next, the
call is transferred automatically. You're unlikely to notice when this
transfer takes place, even though your phone is suddenly switched to a
different radio station and to another channel while you are talking.
Because the cellular signal is low-powered, it doesn't go very far. This
permits the same channel you are talking on to be used for calls in other parts
of the same metropolitan area without interference. This would mean cellular
radio-telephone systems can serve a very large number of customers in an area
because there are more channels than before-and the larger number of channels
are reused.
Unlike local telephone service, which is provided by a monopoly, there is
competition in cellular. Two classes of companies are allowed to offer
cellular telephone service in every market. One cellular system can be owned
by a telephone company, the other by someone else. The two-company rule was
adopted by the FCC so that AT&T, which developed cellular, could not monopolize
the whole thing.
Cellular Telephones come in two basic versions, as car phones and portable
phones, with a briefcase hybrid. Car phones are by far the most common,
because they are much cheaper. But most believe that, ultimately, portables
will be the most popular. Washington Post Company president Richard Simmons,
whose company is a partner in several cellular systems, even predicts that by
the early 1990's "There will be phones roughly the size of a calculators that
you carry around in your pocket. They will cost no more than five hundred
dollars. They will emancipate people from the necessity of locating a phone to
make calls. The bad news is, you will never be able to get away from the phone,
and we'll call it progress."
Car telephones include a small transmitter-receiver unit that is usually
mounted in the trunk, an antenna and a control head that includes the handset.
In most cellular systems, the telephone touchpad is located on the handset.
Many domestic and foreign manufacturers make cellular car phones, but so far
only Motorola makes portables, the DYNA T-A-C 8000X and 8000S. Motorola's
portables look like a slightly enlarged, somewhat chunky telephone handset,
with a stubby antenna at one end.
Portables are less powerful than car units, so they can't be used with some
cellular systems. The portable's other limitation is battery life. A portable
can listen for calls for about eight hours, but it can only transmit for only
thirty minutes. After that time it must be charged for a minimum of an hour.
The following American cities have cellular telephone service or soon will
get it:
New York Denver
Los Angeles Seattle
Chicago Milwaukee
Philadelphia Tampa
Detroit Cincinnati
Boston Kansas City
San Francisco Buffalo
Washington Phoenix
Dallas San Jose
Houston Indianapolis
St. Louis New Orleans
Miami Portland
Pittsburgh Cleveland
San Diego Atlanta
Baltimore Minneapolis
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