The History of ESS Courtesy of the Jolly Roger

Of all the new 1960s wonders of telephone technology -

satellites, ultra modern Traffic Service Positions (TSPS) for

operators, the picturephone, and so on - the one that gave Bell

Labs the most trouble, and unexpectedly became the greatest

development effort in Bell System's history, was the perfection

of an electronic switching system, or ESS.


It may be recalled that such a system was the specific end in

view when the project that had culminated in the invention of the

transistor had been launched back in the 1930s. After successful

accomplishment of that planned miracle in 1947-48, further delays

were brought about by financial stringency and the need for

further development of the transistor itself. In the early 1950s,

a Labs team began serious work on electronic switching. As early

as 1955, Western Electric became involved when five engineers

from the Hawthorne works were assigned to collaborate with the

Labs on the project. The president of AT&T in 1956, wrote

confidently, "At Bell Labs, development of the new electronic

switching system is going full speed ahead. We are sure this will

lead to many improvements in service and also to greater

efficiency. The first service trial will start in Morris, Ill.,

in 1959." Shortly thereafter, Kappel said that the cost of the

whole project would probably be $45 million.


But it gradually became apparent that the developement of a

commercially usable electronic switching system - in effect, a

computerized telephone exchange - presented vastly greater

technical problems than had been anticipated, and that,

accordingly, Bell Labs had vastly underestimated both the time

and the investment needed to do the job. The year 1959 passed

without the promised first trial at Morris, Illinois; it was

finally made in November 1960, and quickly showed how much more

work remained to be done. As time dragged on and costs mounted,

there was a concern at AT&T and something approaching panic at

Bell Labs. But the project had to go forward; by this time the

investment was too great to be sacrificed, and in any case,

forward projections of increased demand for telephone service

indicated that within a phew years a time would come when,

without the quantum leap in speed and flexibility that electronic

switching would provide, the national network would be unable to

meet the demand. In November 1963, an all-electronic switching

system went into use at the Brown Engineering Company at Cocoa

Beach, Florida. But this was a small installation, essentially

another test installation, serving only a single company.

Kappel's tone on the subject in the 1964 annual report was, for

him, an almost apologetic: "Electronic switching equipment must

be manufactured in volume to unprecedented standards of

reliability.... To turn out the equipment economically and with

good speed, mass production methods must be developed; but, at

the same time, there can be no loss of precision..." Another year

and millions of dollars later, on May 30, 1965, the first

commercial electric centeral office was put into service at

Succasunna, New Jersey.


Even at Succasunna, only 200 of the town's 4,300 subscribers

initially had the benefit of electronic switching's added speed

and additional services, such as provision for three party

conversations and automatic transfer of incoming calls. But after

that, ESS was on its way. In January 1966, the second commercial

installation, this one serving 2,900 telephones, went into

service in Chase, Maryland. By the end of 1967 there were

additional ESS offices in California, Connecticut, Minnesota,

Georgia, New York, Florida, and Pennsylvania; by the end of 1970

there were 120 offices serving 1.8 million customers; and by 1974

there were 475 offices serving 5.6 million customers.


The difference between conventional switching and electronic

switching is the difference between "hardware" and "software"; in

the former case, maintenence is done on the spot, with

screwdriver and pliers, while in the case of electronic

switching, it can be done remotely, by computer, from a centeral

point, making it possible to have only one or two technicians on

duty at a time at each switching center. The development program,

when the final figures were added up, was found to have required

a staggering four thousand man-years of work at Bell Labs and to

have cost not $45 million but $500 million!