Voice
Communication in Business Volume 1
Essays on telecommunications,
1969-1980
Chapter 2
Unscrewing the Inscrutable: Some Communications Jargon
One of the problems in
dealing with telecommunications is the obscure dialect spoken by its
practitioners. As a humble attempt to clarify matters, I dashed off
the following. Prepared originally for a local business magazine,
the article was rejected. I sent it to another with similar result.
Ultimately, I sent it to Jerry Goldstone at Business Communications
Review. Jerry didn't like it but, after a few months, he set it in
type to fill a gap in his magazine. At the last minute, a more
worthy article came in, so he lost the copy. Finally, in the
March-April, 1977, issue, he needed to fill some space and the
article finally appeared.
To our mutual surprise,
the IEEE Professional Communication Society asked to reprint the
article (IEEE Transactions on Professional Communications, March
1978), and a gentleman in the National Telecommunications and
Information Administration (part of the U.S. Department of Commerce)
expressed interest in including some of the material in a glossary.
All I was trying to do
was show that a dictionary didn't have to be dull.
***
Telecommunications can be effective as a
cost-cutting tool. Travel and correspondence are becoming more and
more expensive, and neither will ever be quite as fast as an
instantaneous conversation. However, it is not always easy to choose
telecommunication services properly. An eager telco representative,
happily extolling the virtues of Centrex, CCSA, ESS, WATS, FX, etc.,
may make even the best plan seem unlikely. In this age of jargon,
translation can sometimes be helpful. The following are some of the
frequently encountered telephone terms at the moment:
POTS. This stands for "Plain Old
Telephone Service" and refers to standard telephone company
offerings. At one time someone suggested PANS as an acronym for
Private Automatic Networks, describing tie-line systems used by
larger companies; unfortunately, POTS and PANS was too much for
AT&T.
ESS. This means Electronic Switching
System, and it represents a major effort by the telco to escape from
POTS. An ESS is a large machine that sits in a CO (Central Office)
and, upon eating the signals dialed by customers, establishes the
appropriate connections. Because the ESS is part computer, it can be
programmed to do many things in addition to connecting the line of
Peter Smith to that of John Jones. For instance, you can cause an
ESS to transfer a call from your line to another line or, if you are
going to some other nearby location, you can instruct the ESS to
forward your calls to that location. It is not yet certain that
telco customers want to do these things, but if they should, the ESS
can, for a monthly charge, help them out.
Centrex. An ESS is often used to
provide Centrex service. Centrex is not an acronym, but a word
coined to describe a particular service offering: direct inward
dialing (DID) and identified outward dialing (IOD). If you only have
two or three lines, Centrex won't help you. However, if you have a
switchboard with several hundred lines, Centrex takes on more
meaning. With a regular switchboard, all incoming calls must be
answered by a switchboard attendant and then completed to the called
party. DID permits the attendant to be bypassed. IOD allows outgoing
telephone calls to be billed to individual switchboard lines to help
with internal cost allocation. Many companies find this feature
highly desirable when some departments make very little use of the
phone while others use it extensively. QZ billing used to be
available to do this same job, but now it is either no longer
available or so expensive that the per-call billing charge is an
appreciable portion of the total cost. It should be noted that DID
and IOD are in no way related. Often only one or the other is
needed, but not both. Tough luck. They usually come as a package.*
[* FOOTNOTE: New tariffs
in many states will now let you buy DID without AIOD, but only
in a few states can you get AIOD without DID]
AIOD. This is Automatic Identified
Outward Dialing, and is often provided when an ESS offers Centrex
service. Centrex can be provided with many other types of equipment,
however, depending on what equipment the telco has available.
Whether you get AIOD or IOD is a telco option. IOD is handled by
operators—the same ones who used to ask for your QZ billing number.
PBX. PBX stands for Private Branch
Exchange. This means your company's switchboard. If you can dial
through it, some people call it a PABX, where the "A" stands for
automatic. If it is constructed with electronic components like an
ESS, it may even be called an EPABX. Note that PBX is the only
technically correct term. Anything else is either a trade mark or an
affectation.
Trunk. A trunk is a connection from a
PBX to a CO. At the Central Office end, it is called a line since it
looks like any other telephone line. The trunk circuit at the PBX,
however, is very complicated; it lets the switchboard attendant
answer incoming calls, lets you dial "9" to get outside, etc. In the
public telephone network, just to make things complicated, a trunk
is a voice channel between two Central Offices while a line goes to
a customer.
Tie-line. A tie-line* is a voice
channel between two PBXs. It is just like a trunk between two CO's,
except that it is called a line and not a trunk. After all, in a
PBX, a trunk is a channel that connects to a CO where it is called a
line.
[* FOOTNOTE: The proper
terminology ultimately became "tie trunk"]
CCSA. CCSA stands for Common Control
Switching Arrangement, and it refers to a means of switching
tie-lines. Like some kinds of Centrex, the CCSA switching equipment
may be an ESS (although often it is not), and it is located in the
telco's building rather than the customer's. There are much less
expensive ways of switching tie-lines.
FX. An FX line is a Foreign Exchange
line; that is, it is a telephone line that goes to a central office
not the one nearest the customer's location. An FX line can be
terminated on a PBX or Centrex system as well as an ordinary
telephone. When used with a PBX or Centrex, it behaves just like any
other CO trunk, except that it is served by a distant CO.
WATS. WATS stands for Wide Area
Telecommunications Service but, like an FX line, a WATS line is just
a connection to a CO. It can be terminated on a telephone instrument
or on a PBX, again just like an FX line. The difference between a
WATS line and a regular CO trunk is the way in which billing is
carried out. The customer is not billed per call, but by a certain
amount per month for a given number of hours of service, with
overtime charged at a reduced rate. When Centrex is provided by an
ESS, there is actually no specific piece of equipment that can be
called a WATS line. Since WATS is a billing feature, the ESS simply
makes appropriate manipulations in its computer-like program.
If there are other telecommunication terms
that you have been wondering about, send them in. Our team of
professional obfuscators awaits your challenge.
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