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The Digital Future Of The Telephone Network
A Study of Evolving Technology
By Lee Goeller
Originally published by Probe Research Inc. 1979.
Reprinted by permission
Chapter 1
Introduction
Criticism of the telephone company in recent
years has covered a wide range of issues. In most cases, however, it
has not focused on how well the system actually works. By contrast,
many people who have working knowledge of the technical and
operational aspects of the telephone industry have often expressed
open admiration for its achievements in these fields.
However, in recent years, even the most
devoted telephone watcher has found his faith being slowly
undermined. The refusal of the telephone industry to render needed
service brought on the Carterfone decision, and repeated attempts to
pass the "Consumer Communications Reform Act" to invoke both federal
and state law against anyone wishing to render services which the
telephone industry did not care to provide have led to
disillusionment and even bitterness.
In spite of all the interconnect turmoil,
though, there was always the feeling that the public telephone
network was being well managed. And then the other shoe dropped. It
has slowly become evident in recent months that the public network's
major advantages, ubiquity and uniformity, may not be extended into
the future. This is cause for real concern. Further, generality, the
ability to handle a wide variety of communications, is being
seriously limited by questionable economy preserving existing
traditions.
The problem lies in the word "digital."
Advances in technology, notably Large Scale Integration or LSI, have
tended to make digital technologies increasingly attractive when
compared to analog technologies, and have opened the door to many
new possibilities. But, like all new advances, introduction into
existing systems is the main problem. The telephone industry, with
billions invested in equipment required to render service today, has
to plan very carefully to add new and radically different equipment
for service in the future. The task is not easy, but there are
options. What is needed is a good look at the digital future as
planned, contrasted with some of the more obvious possibilities.
Perhaps this will help us to understand why
separate voice and data networks appear to be in the cards; why the
No. 4 ESS, a digital switching system, will be switching analog
trunks for years while No. 1 ESS, an analog switch, will meet
digital trunks in ever increasing quantities; and why Common Channel
Interoffice Signaling or CCIS, a digital signaling system most
useful in connection with analog trunks, is being built into digital
switches with great fanfare. It may also give us insight into why
AT&T insists that cost savings attributed to digital switches are
actually due to stored program control when such savings are
generally considered to come from such factors as the elimination of
separate channel banks in carrier systems, the economical
introduction of station carrier, remote concentrators and PBX
interfaces along with the elimination of hundreds of cross-connect
frames with their attendant space and administration problems. None
of these, of course, has anything to do with stored program control
of switching systems. We may even be able to understand why
transmission standards based on computer simulated user preference
tests which indicate that local calls should be 6 dB louder than
long distance calls are being suggested for local (Class 5) central
offices and how these standards will make digital switching less
attractive for other manufacturers (notably those who supply the
independent telephone industry). We will also see that this same
standard may maintain the segregation between future voice and data
networks by causing direct data transmission (without modems) to be
blocked from the public voice network.
The technical aspects of telephony, although
not particularly difficult, are not generally known even in
engineering circles. There are few textbooks on the subject, and
almost no colleges offer courses that are even vaguely related. Thus
scientific principles have slowly been translated into sacred
mysteries, and high priests, initiated through years of faithfully
following magic rituals, handed down from before the dawn of
telephonic time, have taken over the communications network.
It is my contention that we infidels will not
be struck dead for trying to understand what is going on. We have a
stake in the game that is being played, and we must, in
self-defense, understand how decisions being made by others will
control our lives for decades. There are alternatives, and some of
them must be considered. Communications is too important to be left
exclusively to professional communicators,
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