Privateline.com's Telephone History
(Soundwaves) Next page -->(Life
at Western Electric) next
Prefixes or EXchange Names/ Mobile Telephone
Exchange Names in 1916
- Numbering eras in the United
States for the Bell System
- First telephone numbers are
- Depending on exchange size,
two, three or four digit numbers assigned to subscribers,
- Two letter prefix codes assigned
to four digit numbers (Circa 1928 to 1958)
- In larger cities three letter
prefix codes assigned to four digit numbers (Post WWII)
- Seven digit, all number dialing
begins phase in. (1958)
- Nearly all of North American
telephone network converted to all number dialing (1985?)
- Some party lines remain, with
single digits like Rodeo Creek Number 8
Was it all a mistake? In January, 1958, Wichita Falls, Texas
was the first American city to put in true number calling, that
is, seven numerical digits without letters or names. Although
it took more than fifteen years to implement throughout the Bell
System, ANC, or all number calling, would finally replace the
system of letters and numbers begun forty years before at the
advent of automatic dial.
AT&T's operating companies started installing dial telephones
in the mid to late 1920s. Customers could now dial numbers themselves,
instead of having an operator place them as before. Rather than
use all digits to indicate a telephone number, AT&T hit upon
a hybrid system of letters and numbers. Instead of a number like
351-1017, the Bell System referred to it by a name like ELgin
1-1017, ELliot 1-1017, or ELmwood 1-1017. Something like that.
The two letters and a number indicated a customer's switching
office or exchange, the last four digits the actual customer's
number. But why use letters?
The Bell System thought abbreviations would prevent misdialing,
a mnemonic device to help callers unaccustomed to using dial
telephones. AT&T's William G. Blauvelt designed a dial with
the letters and numbers we use today, one without a Q or Z, one
without letters for the digits 1 and 0. The assumption was, therefore,
that customers could dial four or five numbers correctly but
not six or seven. And that somehow they needed letters as well.
I've never understood, though, why PEnsylvania 6-5000 should
be easier to remember or dial than 436-5000. Yet for forty years
the most bizarre exchange names flooded the country and the entire
telephone system was based on this riot of numbers and letters.
It's with some satisfaction I note that AT&T's Joel
and Schindler, in A History of Engineering and Science
in the Bell System: Switching Technology (1925 -- 1975),
in discussing the Texas trial above, state contritely that "later
human-factors studies showed there was no need for letters in
the dialing sequence." Whoops! They went on to say that
people in 1958 were now used to dialing, quite unlike forty years
before. Four decades of practice were needed before people could
dial another two or three digits? Perhaps. But I doubt it.
The site for all things exchange names:
exchange names: http://ourwebhome.com/TENP/Recommended.html
Without doing a complete research project on this I'd say
the Bell System followed the lead of many Independents who were
using numbered and lettered dials before AT&T. Bell's regional
operating companies may have assumed that letters and numbers
were necessary because they were being used, not because they
were actually needed. Tradition or sloth set in afterwards and
made exchange numbers accepted, unquestioned practice.
The first telephone numbers weren't numbers, they were names.
The name of your company or you as an individual. That was too
confusing to build a telephone system on since many people in
a town might share the same name. Starting in 1879, then, scarcely
three years after the telephone was invented, the switch to assigning
a customer a number began, with a four digit code being typical.
Calls were not dialed by the customer, indeed, there were no
dial telephones yet. All calls were connected manually by an
operator at a switchboard. But dial telephones would come along.
Let's look at how telephone numbers have been arranged recently,
before we look at the numbered and letter scheme of old. Four
digit codes allowed 9,999 possible telephone numbers. Plenty
for a small town but hardly enough for a big city. What to do?
For every block of 9,999 telephone numbers you assign a two or
three digit code ahead of it, to designate the telephone switch,
just as the four digit code identifies the subscriber. We call
the two and then three digit code the prefix or exchange number.
So, if my number was 1017 in one part of town my prefix might
be 203, hence 203-1017. Another customer having the same number
in another part of town would get another prefix number, say,
481, for 481-1017. The numbers 1 and 0 aren't used for prefixes
since so many other things are keyed into those digits. Like
dialing 1 before placing a long distance call and dialing 0 before
connecting to an operator.
We then have eight digits which can't be more than three digits
long. That means 512 possible office or prefix codes. Which works
out to roughly slightly more than five million possible telephone
numbers. That's a good system but the one the Bell System settled
on for decades was quite limiting. Let's look at that.
As I said before, the Bell System first designated prefixes
with letters, not numbers. In the beginning these two letter
abbreviations described the area the switch building or central
office was located in. Like ELm for an Elm street locale or FRanklin
for an exchange on Franklin street. But this sensical method
didn't last long as the few central office codes ran out. The
problem was there were only so many easily pronounced names,
ones where the first two letters of the word wouldn't be confused
with other letters. Exchanges were later named for landmarks,
famous families, city neighborhoods, and so on. After World War
II some two letter prefixes had a number added on to them to
extend their usefulness. Something like PLaza1-1017. That gave
more prefix possibilities.
People eventually knew exchange names belonged to certain
parts of the city and made associations and assumptions based
on your telephone number. Did you live in downtown San Francisco?
Or were you out by Golden Gate Park? Or near the Marina? Your
telephone number gave a clue. All number dialing wiped out all
these names and the memories that went them, much angst ensued,
and countless editorials mourned their loss. Witness this lament
from New York City:
"You could learn about a fella by knowing his exchange.
A MOnument fella was up near 100th Street and West End Avenue.
You could picture him coming downtown on the IRT, strolling first
to 96th and Broadway for the newspapers, passing the Riviera
and Riverside movie theaters (both gone). The ATwater girl was
an East Side girl, a taxi-hailing girl, on her way to her job
at Benton and Bowles. A CIrcle fella was a midtown fella, entering
his CIrcle-7 Carnegie-area office with a sandwich from the Stage
Deli. And what about a SPring-7 girl, twirling the ends of her
long brown hair as she lay on her bed talking to you on te phone?
A Greenwich Village girl. A 777 girl is nothing. She is invisible.
She is without irony, seldom listens to music."
Jonathan Schwartz, New York Magazine, December 21 -- 28, 1987,
as reproduced in Once Upon a Telephone: An Illustrated Social
History, (1994) Stern and Gwathmey, New York. Harcourt Brace
and Company. p.47
As I mentioned at the top of this page, in 1958 The Bell System
began phasing out exchange name dialing or letter prefixes. As
Stern and Gwathmey put it, "the WAlnuts, LOcusts, SPruces
and MAgnolias were just so much dead wood." As of 1977,
nearly two decades later, only 74% of Bell System lines were
ANC or all number calling, it would take years more to complete
the job, removing a system which was never needed in the first
Could you tell me in what year only a 3 digit number was used?
If you want to date something by a telephone number you should
contact the history museum nearest the area your interested in.
Or look in a local library for old phone books or newspapers
with ads that contain telephone numbers. It's really the only
way to determine an approximate date, given how every telephone
company phased exchange names in and then out.
And please note: I know I sound harsh on exchange names; when
I see letters and numbers together my eyes glaze over and I can't
focus on what's being communicated. But many people did find
them useful in remembering a telephone number and millions still
feel sad at their passing; I do not mean to devalue anyone's
nostalgia or emotions. Tom Farley
Exchange Names in 1916
Britain had some wonderful sounding exchange names: BR, Brixton;
HS, Hammersmith; MA, Mayfair; P, Paddington, and so on. The table
and information on the left is from the ultimate Strowger site:
Strowgers and their kin were early automatic telephone switches.
The chart on the right is from Laidlaw and Grinstead's article
The Telephone Service of Large Cities, with Special Reference
to London, presented before the Institution of Electrical Engineers
in London on May 15, 1919. Printed later in the IEE Journal,
Volume 57. (1919)
The Mnemonics System
It was thought that people would have problems
remembering seven digit numbers (3 exchange + 4 subscriber) so
a system of allocating letters to the dial to make area mnemonics
was developed. Each exchange was then given a code according
to the location, as closely as possible. The original British
lettering scheme was as follows :
|Some Examples :
MILl Hill (645)
here for a much larger picture of the above
^top of page^
The Telephone Name EXchange Project by Robert Crowe
(click here to go there)
Letter Prefixes and Numbering Plans/
Mobile Telephone Prefixes
- Pages: Pages:
(Soundwaves) next page -->