John_McNamara_office@es.stratus.com (09/15/89)
Recent postings by Bob Clements and Peter Desnoyers concerning
MIT's Dormitory Telephone Service ("Dormphone") bring to mind a
number of fond memories. Please forgive the mention of specific
names, but it simplifies the telling of the story. In 1914 (?)
a young man named Fredrick E. Broderick went to work for MIT,
which was at that time still located in Boston. By 1918, MIT
had moved to its Cambridge location, and another young man,
Carlton E. Tucker, graduated (his thesis was on the effects of
air pressure on underground trolley car operation, bespeaking an
interest in railroads and transit that lasted all his life).
In addition to his interest in railroads, Carlton Tucker was
very interested in telephones. During the next thirty years, he
rose to full professorship in the MIT Electrical Engineering
department, while simultaneously managing MIT's growing
telephone systems. I say "systems" because there were two: one
rented from New England Telephone, and an MIT-owned system. The
MIT system consisted of a small 100-line SXS system that served
the EE department (providing dial service long before the NET
system went dial in 1941) and two manual switchboards, one in
the graduate student residence (150 lines) and one in the East
Campus dormitories (550 lines). The MIT system was maintained
by Professor Tucker's friend Fred Broderick, who ran an
instrument room in the EE department.
In 1949, MIT built the first of the West Campus undergraduate
dormitories, Baker House. New AECO SXS equipment (300
self-aligning plunger lineswitches, 30 first selectors and 30
connectors) was installed to provide a phone in every one of 250
rooms. In addition, when MIT purchased the nearby Riverbank
Court residental hotel a few years later and converted it into
Burton House / Connor Hall, 25 lines from Baker were run into
that building to provide corridor telephones, each serving about
20 people. Lines from the Baker SXS system appeared at the
Graduate House and East Campus manual boards (only about 4 lines
each). The Baker System was fairly reliable, except that the
lineswitches had a preference chain (of contacts) that often got
dirty, resulting a loss of dial tone for up to 100 users. In
addition, the dial tone generator was really a buzzer, and
occasionally failed. Upon one such occasion, maintenance
personnel replaced it with a tape "Dial Dammit, Dial Dammit".
The Baker system was maintained by students supervised by Fred
Broderick, beginning a tradition / fraternity that would last
for 40 years, half of them under Broderick's direction.
Sometime in the late 50's a student approached Professor Tucker
with the idea of buying some surplus SXS equipment from a South
Sea island location and fully automating the dormitory system,
which at that time consisted of 100 SXS lines in the EE
department, 300 SXS lines in Baker, and about 700 manual lines
in Graduate House and East Campus. Professor Tucker explained
to the student that the freight costs would be excessive, but
the idea stuck in his mind.
In about 1960, when Bob Clements and I were both Freshmen, the
John Hancock Company equipment (3400 lines of AECO SXS) came on
the market. According to one story, MIT dragged their feet
about getting the equipment, and the "newest" equipment had been
sold before Professor Tucker could convince MIT to pick up the
remainder, about 2000 lines. Indeed, three of the 100-line
groups that MIT purchased bore date stickers "1922".
During the 1961-1962 period, Bob Clements and a couple others
(from the original "WTBS" - the MIT station) put the equipment
together, and he and I and others installed dial telephones in
the rooms. On September 1, 1963, the system went completely
dial, with roughly 1500 lines in service. The equipment was
located in three separate locations spread over the campus, and
included non-aligning and self-aligning plunger lineswitches
(see Bob Clement's posting for the difference), linefinders, and
lots of selectors and connectors.
We had lots of variety. Some of the lines in the Graduate House
were party lines with Tip Party / Ring Party selective ringing.
Some of the connector switches were Trunk and Level Hunting, and
were used for dormitory desks and student activities. Power
systems included 70 ampere motor generator sets, large glass
cased batteries, and the motor-driven Variac kludge that Peter
Desnoyer mentioned. (The latter was given to us by NET. It
used a Whetstone bridge circuit that compared the office battery
to a reference battery. Current flow in the center of the
bridge operated polar relays that flipped field capacitors in a
220V motor that operated the Variac. The Variac in turn
regulated Tungar rectifier tubes.)
Since this was 5 years before Carterphone, there was no
connection to the outside world, and there was no operator.
With the advent of Carterphone, various interconnection methods
were employed, including one where the MIT operator (at the NET
owned switchboard) used one cord set to set up the call and
another (via a second jack) when the called party answered.
Needless to say, disconnections were common.
In 1976, the NET PBX (about 7000 lines of SXS) was replaced with
a CO Centrex (1A ESS). Shortly thereafter, direct inward
dialling was installed between the CO and Dormphone, permitting
anyone in the world to call into 40-50 year old equipment. As
Larry Lippman has pointed out, a good ear is an important
maintenance tool, and it was easy to tell the difference between
the slow and irregular dial pulse strings generated by Dormphone
dials, and the crisp and rapid perfectly timed digits incoming
from the ESS.
Since MIT did not want to have to bill the students, all
outgoing calls were credit card / collect / third party, and all
incoming calls were greeted with a recorded message "This is
MIT, collect and third party calls are not accepted at this
number". The recorded message was stored digitally and was the
highest tech thing ever to grace Dormphone. It was also the
subject of several hacks, as people would break into the
exchange and change the recording.
During the late 70's and early 80's, additional dormitories were
added to the West Campus, and equipment was purchased from
American Optical and other sources, to bring the total number of
lines in service up to about 2800.
Meanwhile, the ancient equipment, including the 300 lines of
1922 equipment, continued to serve well past its 40 year design
life, and remained in service until August 1988, when MIT
installed a 5ESS purchased from AT&T. All of the Dormphone
equipment was scrapped. Fred Broderick's name lives on amongst
MIT students as a station at the Tech Model Railroad Club
(recipient of a lot of Western Electric college gift equipment
via Fred). Carlton Tucker's name also is immortalized in a TMRC
station (he was the TMRC faculty advisor), and in a follow-on to
his Wire Communications course, 6.311 Telephony. To me,
Dormphone lives on as the most fun job I ever had.