The Subscriber Telephone Set

8/11/2019 The Subscriber Telephone Set

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The subscriber telephone set consists of the following parts:

1. Microphone2. Receiver

3. Switch connections to the telephone system

4. Ringing circuitry

. !ial networ"

The instrument# which contains the microphone an$ the receiver# is calle$ han$set. The han$set isplace$ on the cra$le when the telephone is not in use. %n this position it opens the switches an$$isconnects the han$set from the telephone system. &n electromagnet# calle$ the ringer isconnecte$ to the telephone line on the e'change si$e# so that a ring can be receive$ from thee'change when it is calle$. The e'change $etermines that whether the telephone is i$le or busy orinitiating a call by monitoring the $c current. & simplifie$ circuit an$ (loc" $iagram of thetelephone set is shown in the figure.

)ircuit $iagram of subscriber*s telephone set

Telephone Set Transmitter

Microphone in telephony is regar$e$ as transmitter.%t is a trans$ucer# which converts soun$ energy intoelectrical energy. There are $ifferent types oftransmitters but carbon granules transmitter is the


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most wi$ely use$ in the han$set of the mo$ern telephony. +e will $iscuss the carbon granuletransmitter only. %t is base$ on the principle that the resistance of carbon granules is inverselyproportional to pressure. The constructional $etails of the carbon transmitter# is illustrate$ in thefigure.

%t is the property of carbon that its resistance varies with pressure. The carbon transmitter $oesnot pro$uce any e.m.f. but only change its resistance with the changing pressure.

)arbon granules are place$ between two electro$es in an insulate$ chamber. ,ne electro$e isfi'e$ to the bac" of the chamber while the other electro$e is attache$ with the movable$iaphragm. The two electro$es are connecte$ with the battery. The transmitter offers an electricalresistance to the flow of current# which is the resistance of the carbon granules. +hen the$iaphragm moves inwar$ an$ outwar$# $ue to soun$ pressure# the pressure on the carbongranules also changes. Thus the resistance of the carbon granules also varies with the changingpressure an$ hence the current flow between the two electro$es also varies. & current variation#correspon$ing to the soun$ pressure.

Telephone Set Receiver

The soun$ repro$ucer in telephony is calle$receiver. The receiver $oes the reverse functionof a transmitter. %t is a $evice# which convertselectrical energy into soun$ energy.Theconstructional $etails of the telephone receiver# isshown in the figure.

%t consists of a $iaphragm# permanent magnet

an$ win$ings. +hen the incoming signal currentpasses through the win$ings# magnetic flu' ispro$uce$. The magnetic flu' follows themagnetic path# which consists of the iron path ofthe permanent magnet# the pole pieces#$iaphragm an$ the two air gaps between the$iaphragm an$ the pole pieces. Thus a varying magnetic pull is pro$uce$# which causes the$iaphragm to vibrate in accor$ance with the signal current receive$ an$ hence pro$uce the soun$.The permanent magnet is use$ to polari-e the receiver. The pull on the $iaphragm $epen$s uponthe magnetic flu' $ensity in the air gaps between the $iaphragm an$ the pole pieces. Thusma'imum change will be pro$uce$ when the current changes in the coil.

Side Tone

+hen we spea" in front of the telephone transmitter# .we hear our own voice in the receiver as afee$bac". +ith the help of this fee$bac" we are able to a$ust the volume of our voice accor$ingto $ifferent situations. +hen the level of this fee$bac" is high# we lower our voice an$ when it islow. we spea" lou$er This fee$bac" voice is calle$ si$e tone.


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Si$e tone may be $efine$ as the repro$uction of soun$ in the receiver pic"e$ up from theassociate$ transmitter. ,r the amount of voice power couple$ from the transmitter to the receiverof the same telephone.

Too much si$e tone an$ complete absence of it is un$esirable. %n the former case# the spea"er will

"eep his level of volume of voice very low an$ hence will affect the output of the transmitter. %nthe latter case# the telephone will/appear $ea$ to the subscriber an$ this is a very uncomfortablefeeling.

The $esirable amount of si$e tone is that which we have in our $aily free air conversation witheach other across the table.

Antiside Tone Circuit

To control the level of the si$e tone to the $esirable amount anti/si$e ton in$uction coil0&.S.T.%.) is use$ in the subscriber*s telephone set. The anti/si$e tone in$uction coil serves the

following.

1. )ontrol the level of the si$e tone to the $esirable amount.2. nsures that no $c current flows through the receiver.

3. Matching between the impe$ances of the transmitter an$ receiver with that of the line.& simple circuit arrangement for the re$uction of si$e tone is shown in the igure.

The principle of the arrangement can be e'plaine$ as follow.

)onsi$er the figure 0& in this case the transmitter is transmitting.%f

b 5 i 6 71 5 72

then the transmitter current $ivi$es e8ually in 71an$ 72. The magnetic fiel$ pro$uce$ by thesetwo win$ings will be e8ual an$ opposite an$ hence cancel each other*s effect# thus no emf isin$uce$ in 71 an$ the si$e tone is completely eliminate$. 9ractically 71an$L2 are not e'actlye8ual an$ hence some emf is in$uce$ in 71# thus the receiver receives a portion of transmittercurrent. %n figure 0( the receiving current passes through 7% an$ 72. the magnetic fiel$ pro$uce$are in the same $irection an$ reinforce$ each other*s effect. &n emf is in$uce$ in the receivercircuit an$ current flows through the receiver.

The anti si$e tone circuit is mo$ifie$ to ma"e it more 9ractical an$ this mo$ifie$ circuit is shownin the figure.The tree win$ings 71# 72 an$ 73 are magnetically couple$. 71an$ 72 are not e8ual an$ hence anemf is in$uce$ in 73 from the transmitter. The value of R# across which the receiver is connecte$#is such that the voltage $rop across it is e8ual an$ opposite to the emf in$uce$ in 73. This resultsin a much re$uce$ si$e tone in the receiver.


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Magneto Bell

(ell is a means of signaling. +hen the calling party wantsto call the calle$ party. e must first give him a bell to$raw his attention. or this purpose magneto bells use$ inthe telephone set of each subscriber. The magneto bellwor"s on &) supplie$ by the e'change. Theconstructional $etail of the magneto bell is shown in thefigure .%t consists of a permanent magnet# two win$ingson the two legs of the iron yo"e an$ an armature with ahammer. The static flu' pro$uce$ by the permanentmagnet complete their path through the two parallelmagnetic circuits. &s the static fiel$ in each circuit ise8ual# thus the armature remains stationary. +henalternating current flows through the win$ings#electromagnets are pro$uce$. The two fiel$s interact with each other# supporting at one si$e an$wea"ening at the other alternatively. The armature is attracte$ by the stronger magnetic fiel$ an$the hammer stri"es the gongs alternatively# thus pro$uce a soun$.

Basics Of Communication

What is communication?

)ommunication is the means of transferring a message from a source to $estination in it;s original form at the most economical rate.


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The

Telephone Instrument

The Telephone is an instrument that converts soun$ to electrical pulses 6 vice versa.

%t is $esigne$ to carry voice signals from one point to another

%t has a permissible fre8uency range of 3


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This boo" provi$es an intro$uction to the $ifferent types of private telephonesystems# how they operate an$ common call processing features they offer.9rivate telephone systems are communication e8uipment an$ software that areowne$# lease$ or operate$ by the companies that use these systems.

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Sample Diagrams

There are !e'planatory $iagrams in this boo"

Analog and Digital Telephone Stations

This $iagram shows the $ifference between stan$ar$ analog telephone stationsan$ more a$vance$ 9(B stations. This $iagram shows that analog telephonesreceive their power $irectly from the telephone line an$ $igital 9(B telephonesre8uire a control section that gets its power from the 9(B system. &nalogtelephones also use in/ban$ signaling to sense comman$s 0e.g.# ring signals an$to sen$ comman$s 0e.g.# sen$ $iale$ $igits. !igital telephones use out/of/ban$signaling on separate communication lines to transfer their control information0e.g.# calling number i$entification.
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WHAT IS DTMF?

When you press a button in the telephone set keypad, a connection is madethat generates a resultant signal o t!o tones at the same time" These t!o tones

are taken rom a ro! re#uency and a column re#uency" The resultant re#uencysignal is called $Dual Tone Multiple Frequency$" These tones are identical and

uni#ue"

A DTMFsignal is the algebraic sum o t!o dierent audio re#uencies, and

can be e%pressed as ollo!s&

't( ) A*sin'+-at( . /*sin'+-bt( . """"""""""" 00000001'2(

Where aand bare t!o dierent audio re#uencies !ith A and / as theirpeak amplitudes and as the resultant DTMF signal" abelongs to the lo!

re#uency group and bbelongs to the high re#uency group"

3ach o the lo! and high re#uency groups comprise our re#uencies rom

the 4arious keys present on the telephone keypad5 t!o dierent re#uencies, one

rom the high re#uency group and another rom the lo! re#uency group are usedto produce a DTMF signal to represent the pressed key"

The amplitudes o the t!o sine !a4es should be such that

'*"6 7 'A8/( 7 *"9(: 000000001'+(

The re#uencies are chosen such that they are not the harmonics o each

other" The re#uencies associated !ith 4arious keys on the keypad are sho!n inigure 'A("

When you send these DTMF signals to the telephone e%change through

cables, the ser4ers in the telephone e%change identiies these signals and makesthe connection to the person you are calling"

The ro! and column re#uencies are gi4en belo!&


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Fig 'A(

When you press the digit ; in the keypad it generates a resultant tonesignal !hich is made up o re#uencies 66*H< and 2==>H H< is the same" These signals are digital signals !hich aresymmetrical !ith the sinusoidal !a4e"

A Typical re#uency is sho!n in the igure belo!&

Figure '/(

Along !ith these DTMF generator in our telephone set pro4ides a set o

special purpose groups o tones, !hich is normally not used in our keypad" These

tones are identiied as A, /, B, D" These re#uencies ha4e the same columnre#uency but uses ro! re#uencies gi4en in the table in igure 'A(" These tonesare used or communication signaling"

The re#uency table is as ollo!s&


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Figure 'B(

Due to its accuracy and uni#ueness, these DTMF signals are used in controlling

systems using telephones" /y using some DTMF generating IBCs 'M92+2E,M92+2E, etc( !e can generate DTMF tones !ithout depending on the telephone

set"

%n a !eca$ic 9ulse !ialing# also calle$ 7oop !isconnect !ialing# a !irect/)urrent 9ulse Train#representing each !igit# is pro$uce$ by interrupting a continous Signal accor$ing to a $efine$Ratio. igure 1 shows a !eca$ic 9ulse Telephone.

igure 1: !eca$ic 9ulse Telephone

& !eca$ic 9ulse Telephone is e8uippe$ with a Rotary !ial with a inger 9late over it. The Rotary!ial is $esigne$ to sen$ lectrical 9ulses. igure 2 shows the )ircuit of a 9ulse Telephone. The 3spring contacts: the %mpulsing )ontact 0%)T# the (ypass Switch 1 0(91 an$ the (ypass Switch2 0(92 are mounte$ insi$e the Rotary !ial.


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igure 2: The Telephone is Rea$y to ma"e a )all when the oo" Switch is )lose$. The an$setis ,ff the oo".

Ma"ing a )all:

+hen the )ustomer lifts the an$set 0,ff oo"# the oo" Switch is close$ an$ a !) 7oopbetween the Telephone 'change an$ the )ustomer is forme$# igure 1. Therefore# a )ontinous)urrent !) flows through the 7oop.

+hile !ialing a =umber# for e'ample# # the !ial is $rawn roun$ in the )loc"wise

!irection to the inger Stop 9osition an$ release$. The inger 9late will then return to theRest 9osition un$er the influence of a spring. Meanwhile# the (92 in the Rotary !ial isclose$ to ma"e a Short )ircuit# thus you hear no $isturbance in the arphone $uring!ialing.

The %)T then generates the !ial 9ulses by closing an$ opening itself to interrupt the !)

)urrent loop. The number of interruptions is e8uivalent to the !iale$ !igit. This type of

Telephone generates two a$$itional 9ulses# which are eliminate$ by the (91. (esi$es# there is also a mechanical $evice calle$ )entrifugal Covernor# mounte$ insi$e

the Rotary !ial# it helps to maintain a uniform spee$ of rotation.

&fter finishing !ialing# the 9ulses are then $eco$e$ at the Telephone 'change that ma"e

a connection to the )alle$ )ustomer. The Aoice Signals from the )ustomer will betransmitte$ to the arphone through an %solating Transformer. The arphone is connecte$to the Secon$ary +in$ing of the %solating Transformer. This protects the arphone frombeing $amage$ by !) )urrent. The Transformer also provi$es an lectrical %solationbetween the Telephone 'change an$ the ar. %n a$$ition# two anti/parallel !io$esprotects the ar from too much =oise. %f the Aoltage in the Secon$ary +in$ing is over a

certain level# one of the !io$es starts to )on$uct an$ ma"es a Short )ircuit for thearphone.

+hile tal"ing to the Microphone# the Soun$ Signal is transmitte$ to the )alle$ )ustomer

through the Telephone 'change.

Receiving a )all:


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+hen the an$set is on the )ra$le# the Telephone is sai$ to be D,n the oo"D# or rea$y toreceive a )all# igure 3. The oo" Switch is opene$ an$ the path to the right part of the circuit is$isconnecte$.

+henever there is an %ncoming )all# &n &) Ringing Signal from the Telephone

'change is transmitte$ to the Telephone. The Ringing Signal is generally 1< m& &)Signal# with a re8uency between 2< an$ 2 -# that activates an lectromagnet whichoperates a small ammer to stri"e the (ells.

igure 3: The Telephone is Rea$y to receive a )all when the oo" Switch is ,pene$. Thean$set is ,n the oo".

The !TM Telephone# as its name implie$# is base$ on a concept "nown as !ual Tone Multi/re8uency 0!TM# igure 1. %t generates a combination of two Tones for each !iale$ !igit# an$sen$s the !igits to the Telephone 'change by earable Tones instea$ of lectrical 9ulses as in!eca$ic 9ulse Telephone.

igure 4: !TM Telephone

The !TM Telephone is e8uippe$ with a 9ushbutton !ial# in which 1< !ialing !igits 0< throughE# the Star F G an$ the 9oun$ FHG symbols are assigne$ to specific 9ushbuttons. The 9ushbuttons


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are arrange$ in an two/$imensional array with four Rows an$ three )olumns# as shown in igure2. ach Row an$ ach )olumns is assigne$ a Tone of a specific re8uency# the )olumns havingTones of higher re8uencies an$ the Rows having Tones of lower re8uencies. +hen a (utton ispushe$# a !ual/Tone Signal is generate$. This Signal is a combination of Two Tones of $ifferentre8uencies# one from the 7ower re8uency Croup an$ the other from the Ipper re8uency

Croup# an$ it is the reason for calling it F!ual Tone Multi/re8uencyG. %n this way# J 04 K 3Tones of $ifferent re8uencies are use$ to generate 12 04 ' 3 combinations. or e'ample#pushing the (utton FG# the Tones of JJ< - an$ 133? - are transmitte$ together to theTelephone 'change. This Signal is $eco$e$ by the Telephone 'change in or$er to $eterminewhich !igit was !iale$.

igure : The 9ushbutton !ial an$ its correspon$ing re8uencies 9airs

Ma"ing a )all:

+hen the )ustomer lifts the an$set 0,ff oo"# the oo" Switch is close$ an$ a )ircuitconnection between the Telephone 'change an$ the )ustomer Telephone is forme$.

"eneration of Signaling Tones

&s has been sai$# the operation of any 9ushbutton generates a Signal compose$ of Two

Tones# which last as long as the (utton is pushe$. igure 3 shows the )ircuit of a !TMTelephone.


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igure ?: The Telephone is Rea$y to ma"e a )all when the oo" Switch is )lose$. Thean$set is ,ff the oo"

There are two ,scillation )ircuits for generating Tones at $ifferent re8uencies. ach)ircuit consists of a Three/win$ing )oil 0 &*# &D an$ (# (*# (D an$ a )apacitor 0)&an$ )(. +in$ings & an$ ( have a number of Spring )ontacts# $ivi$e$ in to Croup L&an$ Croup L(. There are seven )ran"s un$er the 9ushbutton !ial# they are shown as the$otte$ lines in igure 3# four of them correspon$s to Rows an$ three to )olumns. Theoperation of pushing a (utton results in the actuation of a ori-ontal )ran" an$ a Aertical)ran". +hen a )ran" is actuate$# it will close the correspon$ing Spring )ontact. Theclosure of one of the L& an$ one of the L( )ontacts connects each )apacitor to one ofthe taps on the associate$ +in$ing & an$ (. %n this way# the ,scillation )ircuitscorrespon$ing to the !iale$ =umber are setup.

Then# the actuation of the ori-ontal )ran"s will also put a )ommon Switch L besi$e the

9ushbutton &rray in motion. The )ommon Switch L will operate a set of )ontacts inse8uential or$er as liste$ in igure 3. The or$er an$ function of each )ontact is state$ inthe following:

1. &ttenuates the !ial Tones in the arphone so the )ustomer hears the !ial Signalat a comfortable level.

2. 9owers up the Transistor.


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3. !isables the Microphone so that no other =oise is receive$ from it to interfere the!ial Signal.

4. %nitiates the !ual/Tone Signal from the ,scillation )ircuits. This Signal issustaine$ by ee$bac" &mplification through the Transistor an$ the Transformeraction between the Secon$ary 0&*# (* an$ Tertiary +in$ings 0&D# (D of each

)oil.

The whole Signal Ceneration )ircuit is mounte$ on the bac" of the 9ushbutton 9anel#

ma"ing the 9ushbutton !ial a self/containe$ unit that can be substitute$ for the Rotary!ial in a !eca$ic 9ulse Telephone. The other parts of a !TM Telephone are similar tothose of a !eca$ic 9ulse Telephone# thus the process of Ma"ing an$ Receiving a )all issimilar to that of a 9ulse Telephone. &t the Telephone 'change# the Tones are $eco$e$an$ a )onnection is ma$e to the )alle$ )ustomer.

Receiving a )all:

+hen the an$set is on the )ra$le# the Telephone is sai$ to be D,n the oo"D# or rea$y toReceive a )all. That is# the oo" Switch in igure 3 is opene$ an$ the path to the right part of the)ircuit is $isconnecte$.

+henever there is an %ncoming )all# &n &) Ringing Signal from the Telephone 'change istransmitte$ to the Telephone. The Ringing Signal is generally 1< m& &) Signal# with are8uency between 2< an$ 2 -# that activates a pair of lectromagnet which operates a smallammer to stri"e the (ells.

%n 1>J?# &le'an$er Craham (ell ma$e the first Telephone# calle$ the (ell Telephone# igure 1.Telephone comes from the Cree" wor$ Ftele#G meaning Ffrom afarG# an$ FphoneG# meaning voice

or voice$ soun$.

igure 1: (ell Telephone


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The main parts of the (ell Telephone are: an %ron !iaphragm with attache$ 9ermanent Magnetan$ a )oil of )opper +ires# igure 2.

igure 2: )ross Section of the (ell 9hone

(y tal"ing to the Sen$er;s Telephone# the voice of the Sen$er ma"es the !iaphragm vibrating.Since the Magnet is attache$ on the !iaphragm# the vibration of the !iaphragm also ma"es theMagnet vibrating in the )oil an$ a )urrent is in$uce$. This %n$uce$ )urrent signal is then sent tothe Receiver;s Telephone through the )opper +ires.

&t the Receiver;s Telephone# the process is vice versa. The Telephone ta"es the %n$uce$ )urrentsignal an$ translates it bac" into physical vibrations of the !iaphragm. The Soun$ is repro$uce$an$ can be hear$.

Telephone #istor$

%arl$ Telephone Development
http://www.privateline.com/mt_telephonehistory/http://www.privateline.com/mt_telephonehistory/


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or more information on 7ey$en ars# inclu$ing photographs an$ instructions on how to buil$them# go this page at the Static Cenerator site:

http:www.alas"a.netNnatn"ellley$en.htm

& static electricity web page is here: http:www.sciencema$esimple.comstatic.html

%n 1J2E nglish chemist Stephen Cray transmitte$ electricity over a wire. e sent charges nearly3


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light cities# or provi$e heat. &n$ although batteries woul$ wor" telegraph an$ telephone systems#an$ still $o# transmitting speech re8uire$ un$erstan$ing two relate$ elements# namely# electricityan$ magnetism.

%n 1>2< !anish physicist )hristian ,erste$ $iscovere$ electromagnetism# the critical i$ea nee$e$

to $evelop electrical power an$ to communicate. %n a famous e'periment at his Iniversity of)openhagen classroom# ,erste$ pushe$ a compass un$er a live electric wire. This cause$ itsnee$le to turn from pointing north# as if acte$ on by a larger magnet. ,erste$ $iscovere$ that anelectric current creates a magnetic fiel$. (ut coul$ a magnetic fiel$ create electricityP %f so# a newsource of power bec"one$. &n$ the principle of electromagnetism# if fully un$erstoo$ an$applie$# promise$ a new era of communication

or an e'cellent summary of )hristian ,erste$*s life# visit:http:www.longman.co.u"ttQsecsciresourcesscimonmarQ21 Michael ara$ay reverse$ ,erste$*s e'periment an$ in so $oing $iscovere$ in$uction. e

got a wea" current to flow in a wire revolving aroun$ a permanent magnet. %n other wor$s# amagnetic fiel$ cause$ or in$uce$ an electric current to flow in a nearby wire. %n so $oing#ara$ay ha$ built the worl$*s first electric generator. Mechanical energy coul$ now be converte$to electrical energy. %s that clearP This is a very important point.

The simple act of moving ones* han$ cause$ current to move. Mechanical energy into electricalenergy. &lthough many years away# a turbine powere$ $ynamo woul$ let the power of flowingwater or burning coal pro$uce electricity. Cot a river or a $amP The water spins the turbineswhich turns the generators which pro$uce electricity. The more water you have the moregenerators you can a$$ an$ the more electricity you can pro$uce. Mechanical energy intoelectrical energy.

0(y comparison# a motor turns electrical energy into mechanical energy. Than"s to &. &lmoianfor pointing out this "ey $ifference an$ to =eal Lling for another correction.

)lic" here for a clear# large $iagram on turning mechanical energy into electrical energy.&n$ it*s a goo$ science fair i$ea

% also have a page on easy to $o electrical e'periments for "i$s&gain# goo$ science fair i$eas.
http://www.longman.co.uk/tt_secsci/resources/scimon/mar_01/oersted.htmhttp://www.privateline.com/PCS/hawks4.htmhttp://www.privateline.com/TelephoneHistory/generatingelectricity.htmhttp://www.privateline.com/kids/projects.htmlhttp://www.longman.co.uk/tt_secsci/resources/scimon/mar_01/oersted.htmhttp://www.privateline.com/PCS/hawks4.htmhttp://www.privateline.com/TelephoneHistory/generatingelectricity.htmhttp://www.privateline.com/kids/projects.html


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ara$ay wor"e$ through $ifferent electrical problems in the ne't ten years# eventually publishinghis results on in$uction in 1>31. (y that year many people were pro$ucing electrical $ynamos.(ut electromagnetism still nee$e$ un$erstan$ing. Someone ha$ to show how to use it forcommunicating.

or more information on Michael ara$ay# visit the =) at:http:www.enc.orgfeaturescalen$arunit1E#1E?#


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rom the !ecember# 1E?3 &merican eritage maga-ine# Da s"etch of enry*s primitive telegraph#a $o-en years before Morse# reveals the essential components: an electromagnet activate$ by a$istant battery# an$ a pivote$ iron bar that moves to ring a bell.D See the two boo"s liste$ to theleft for more information.

%n 1>3J Samuel Morse invente$ the first wor"able telegraph# applie$ for its patent in 1>3># an$was finally grante$ it in 1>4>. oseph enry helpe$ Morse buil$ a telegraph relay or repeater thatallowe$ long $istance operation. The telegraph later helpe$ unite the country an$ eventually theworl$. =ot a professional inventor# Morse was nevertheless captivate$ by electrical e'periments.%n 1>32 he hear$ of ara$ay*s recently publishe$ wor" on in$uctance# an$ was given anelectromagnet at the same time to pon$er over. &n i$ea came to him an$ Morse 8uic"ly wor"e$out $etails for his telegraph.

&s $epicte$ below# his system use$ a "ey 0a switch to ma"e or brea" the electrical circuit# abattery to pro$uce power# a single line oining one telegraph station to another an$ anelectromagnetic receiver or soun$er that upon being turne$ on an$ off# pro$uce$ a clic"ing noise.e complete$ the pac"age by $evising the Morse co$e system of $ots an$ $ashes. & 8uic" "eytap bro"e the circuit momentarily# transmitting a short pulse to a $istant soun$er# interprete$ by

an operator as a $ot. & more lengthy brea" pro$uce$ a $ash.

Telegraphy became big business as it replace$ messengers# the 9ony 'press# clipper ships an$every other slow pace$ means of communicating. The fact that service was limite$ to +esternInion offices or large firms seeme$ har$ly a problem. &fter all# communicating over long$istances instantly was otherwise impossible. @et as the telegraph was perfecte$# man*s thoughtsturne$ to speech over a wire.


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%n 1>4 )harles (ourseul wrote about transmitting speech electrically in a well circulate$ article.%n that important paper# the (elgian/born rench inventor an$ engineer $escribe$ a fle'ible $is"that woul$ ma"e an$ brea" an electrical connection to repro$uce soun$. (ourseul never built aninstrument or pursue$ his i$eas further.

or more information on (ourseul an$ early communications in general# vist this Cerman site:http:www.fht/esslingen.$etelehistory1>J?1 ohann 9hillip Reis complete$ the first non/wor"ing telephone. Tantali-ingly close torepro$ucing speech# Reis*s instrument conveye$ certain soun$s# poorly# but no more than that. &Cerman physicist an$ school teacher# Reis*s ingenuity was un8uestione$. is transmitter an$receiver use$ a cor"# a "nitting nee$le# a sausage s"in# an$ a piece of platinum to transmit bits ofmusic an$ certain other soun$s. (ut intelligible speech coul$ not be repro$uce$. The problem

was simple# minute# an$ at the same time monumental. is telephone relie$ on its transmitter*s$iaphragm ma"ing an$ brea"ing contact with the electrical circuit# ust as (ourseul suggeste$#an$ ust as the telegraph wor"e$. This approach# however# was completely wrong.

Repro$ucing speech practically relies on the transmitter ma"ing continuous contact with theelectrical circuit. & transmitter varies the electrical current $epen$ing on how much acousticpressure it gets. Turning the current off an$ on li"e a telegraph cannot begin to $uplicate speechsince speech# once flowing# is a fluctuating wave of continuous characterO it is not a collection ofoff an$ on again pulses. The Reis instrument# in fact# wor"e$ only when soun$s were so soft thatthe contact connecting the transmitter to the circuit remaine$ unbro"en. Speech may havetravele$ first over a Reis telephone however# it woul$ have $one so acci$entally an$ againstevery principle he thought woul$ ma"e it wor". &n$ although acci$ental $iscovery is the stuff ofinvention# Reis $i$ not reali-e his mista"e# $i$ not un$erstan$ the principle behin$ voicetransmission# $i$ not $evelop his instrument further# nor $i$ he ever claim to have invente$ thetelephone.

The $efinitive boo" in nglish on Reis is:Thompson# Silvanus 9. 9hillip Reis: %nventor of The Telephone. .6.=. Spon. 7on$on. 1>>3

or other views an$ e'planations of the Reis instrument# visit &$ventures in )ybersoun$:http:www.acmi.net.au&%)R%SQ(%,.html 0e'ternal lin"
http://www.fht-esslingen.de/telehistory/1870-.htmlhttp://www.privateline.com/kids/projects.htmlhttp://www.privateline.com/kids/projects.htmlhttp://www.acmi.net.au/AIC/REIS_BIO.htmlhttp://www.fht-esslingen.de/telehistory/1870-.htmlhttp://www.privateline.com/kids/projects.htmlhttp://www.privateline.com/kids/projects.htmlhttp://www.acmi.net.au/AIC/REIS_BIO.html


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%n the early 1>J


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DReversing the polarity of the voltages reverses the $irection of $isplacement. The termpie-oelectricity is $erive$ from the Cree" wor$ pie-ein meaning to press. ence# a pie-oelectriccrystal is one capable of pro$ucing electricity when subecte$ to pressure.D

&n anonymous writer in the uly# 1E?4 7en"urt !emo$ulator

&nalog an$ $igital signals compare$ an$ contraste$

&nalog transmission in telephone wor"ing. &t the top of the illustration we $epict $irect currentas a flat line. !.). is the stea$y an$ continuous current your telephone company provi$es. Themi$$le line shows what tal"ing loo"s li"e. &s in all things analog# it loo"s li"e a wave. The thir$line shows how tal"ing varies that $irect current. @our voice varies the telephone line*s electricalresistance to represent speech. )lic" here for another $iagramthat complements this illustration.

(elow is a simplifie$ view of a $igital signal. )urrent goes on an$ off. =o wave thing. There wasno chance the Reis telephone $escribe$ above coul$ transmit intelligible speech since it coul$ notrepro$uce an analog wave. @ou can*t $o that ma"ing an$ brea"ing a circuit. & pulse in this case isnot a wave 0internal lin"%t was not until the early 1E??>. &n e'pertelectrician# he co/foun$e$ Cray an$ (arton# ma"ers of telegraph e8uipment. The +estern Inion
http://www.privateline.com/TelephoneHistoryA/TeleHistoryA.htm#anchor22843956http://www.privateline.com/TelephoneHistoryA/TeleHistoryA.htm#anchor22843956http://www.privateline.com/TelephoneHistory/soundwaves.htmlhttp://www.privateline.com/PCS/modulation.htmhttp://www.privateline.com/PCS/modulation.htmhttp://www.privateline.com/OSP/No.htmlhttp://www.privateline.com/mt_telephonehistory/2006/01/early_telephone_development.htmlhttp://www.privateline.com/mt_telephonehistory/2006/01/early_telephone_development.html#commentshttp://www.privateline.com/TelephoneHistoryA/TeleHistoryA.htm#anchor22843956http://www.privateline.com/TelephoneHistory/soundwaves.htmlhttp://www.privateline.com/PCS/modulation.htmhttp://www.privateline.com/PCS/modulation.htmhttp://www.privateline.com/OSP/No.htmlhttp://www.privateline.com/mt_telephonehistory/2006/01/early_telephone_development.htmlhttp://www.privateline.com/mt_telephonehistory/2006/01/early_telephone_development.html#comments


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Telegraph )ompany# then fun$e$ by the Aan$erbilts an$ .9. Morgan# bought a one/thir$ interestin Cray an$ (arton in 1>J2. They then change$ its name to the +estern lectric Manufacturing)ompany# with Cray remaining an important person in the company. To Cray# transmittingspeech was an interesting goal but not one of a lifetime.

&le'an$er Craham (ell# on the other han$# saw telephony as the $riving force in his early life.e became consume$ with inventing the telephone. (orn in 1>4J in $inburgh# Scotlan$#Craham was raise$ in a family involve$ with music an$ the spo"en wor$. is mother painte$ an$playe$ music. is father originate$ a system calle$ visible speech that helpe$ the $eaf to spea".is gran$father was a lecturer an$ speech teacher. (ell*s college courses inclu$e$ lectures onanatomy an$ physiology. is entire e$ucation an$ upbringing revolve$ aroun$ the mechanics ofspeech an$ soun$. Many years after inventing the telephone (ell remar"e$# D% now reali-e that %shoul$ never have invente$ the telephone if % ha$ been an electrician. +hat electrician woul$have been so foolish as to try any such thingP The a$vantage % ha$ was that soun$ ha$ been thestu$y of my life // the stu$y of vibrations.D

%n 1>J< (ell*s father move$ his family to )ana$a after losing two sons to tuberculosis. e hope$the )ana$ian climate woul$ be healthier. %n 1>J3 (ell became a vocal physiology professor at(oston )ollege. e taught the $eaf the visual speech system $uring the $ay an$ at night hewor"e$ on what he calle$ a harmonic or musical telegraph. Sen$ing several messages at onceover a single wire woul$ let a telegraph company increase their sen$ing capacity without havingto install more poles an$ lines. &n inventor who ma$e such a $evice woul$ reali-e a greateconomy for the telegraph company an$ a fortune for his or her self. amiliar with acoustics# (ellthought he coul$ sen$ several telegraph messages at once by varying their musical pitch. Soun$o$$P %*ll give you a cru$e e'ample# a piano analogy# since +atson sai$ (ell playe$ the piano well.

%magine playing Morse co$e on the piano# stri"ing $ots an$ $ashes in mi$$le ). Then imaginethe instrument wire$ to a $istant piano. Stri"ing mi$$le ) in one piano might cause mi$$le ) tosoun$ in the other. =ow# by playing Morse co$e on the & or ) "eys at the same time you mightget the $istant piano to $uplicate your playing# sen$ing two messages at once. 9erhaps. (ell $i$n*te'periment with pianos# of course# but with $ifferently pitche$ magnetic springs. &n$ instea$ ofust sen$ing two messages at once# (ell hope$ to sen$ thirty or forty. The harmonic telegraphprove$ simple to thin" about# yet ma$$eningly $ifficult to buil$. e labore$ over this $evicethroughout the year an$ well into the spring of 1>J4.

Then# at a frien$*s suggestion# he wor"e$ that summer on a teaching ai$ for the $eaf# a gruesome$evice calle$ the phonoautograph# ma$e out of a $ea$ man*s ear. Spea"ing into the $evice cause$the ear*s membrane to vibrate an$ in turn move a lever. The lever then wrote a waveli"e pattern ofthe speech on smo"e$ glass. Igh. Many say (ell was fascinate$ by how the tiny membranecause$ the much heavier lever to wor". %t might be possible# he speculate$# to ma"e a membranewor" in telephony# by using it to vary an electric current in intensity with the spo"en wor$. Sucha current coul$ then replicate speech with another membrane. (ell ha$ $iscovere$ the principle ofthe telephone# the theory of variable resistance# as $epicte$ below. (roo"sU (ut learning to applythat principle correctly woul$ ta"e him another two years.


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(ell continue$ harmonic telegraph wor" through the fall of 1>J4. e wasn*t ma"ing muchprogress but his tin"ering gathere$ attention. Car$iner Creene ubbar$# a prominent (ostonlawyer an$ the presi$ent of the )lar"e School for The !eaf# became intereste$ in (ell*se'periments. e an$ Ceorge San$ers# a prosperous Salem businessman# both sense$ (ell might

ma"e the harmonic telegraph wor". They also "new (ell the man# since (ell tutore$ ubbar$*s$aughter an$ he was helping San$er*s $eaf five year ol$ son learn to spea".

%n ,ctober# 1>J4# Creen went to +ashington !.). to con$uct a patent search. in$ing noinvention similar to (ell*s propose$ harmonic telegraph# ubbar$ an$ San$ers began fun$ing(ell. &ll three later signe$ a formal agreement in ebruary# 1>J# giving (ell financial bac"ing inreturn for e8ual shares from any patents (ell $evelope$. The trio got along but they woul$ havetheir problems. San$ers woul$ court ban"ruptcy by investing over W1J# (ell tol$ +atson D%f % can get a mechanismwhich will ma"e a current of electricity vary in its intensity as the air varies in $ensity when asoun$ is passing through it# % can telegraph any soun$# even the soun$ of speech.D agenU ecommunicate$ the same i$ea in a letter to ubbar$# who remaine$ unimpresse$ an$ urge$ (ell towor" har$er on the telegraph. (ut having at last articulate$ the principle of variable resistance#(ell was getting much closer.


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,n une 2# 1>J# (ell an$ +atson were testing the harmonic telegraph when (ell hear$ a soun$come through the receiver. %nstea$ of transmitting a pulse# which it ha$ refuse$ to $o in any case#the telegraph passe$ on the soun$ of +atson pluc"ing a tune$ spring# one of many set at $ifferentpitches. ow coul$ that beP Their telegraph# li"e all others# turne$ current on an$ off. (ut in thisinstance# a contact screw was set too tightly# allowing current to run continuously# the essential

element nee$e$ to transmit speech. (ell reali-e$ what happene$ an$ ha$ +atson buil$ atelephone the ne't $ay base$ on this $iscovery. The Callows telephone# so calle$ for its$istinctive frame# substitute$ a $iaphragm for the spring. @et it $i$n*t wor". & few o$$ soun$swere transmitte$# yet nothing more. =o speech. !isheartene$# tire$# an$ running out of fun$s#(ell*s e'perimenting slowe$ through the remain$er of 1>J.

!uring the winter of 1>J an$ 1>J? (ell continue$ e'perimenting while writing a telephonepatent application. &lthough he ha$n*t $evelope$ a successful telephone# he felt he coul$ $escribehow it coul$ be $one. +ith his i$eas an$ metho$s protecte$ he coul$ then focus on ma"ing itwor". ortunately for (ell an$ many others# the 9atent ,ffice in 1>J< $roppe$ its re8uirementthat a wor"ing mo$el accompany a patent application. ,n ebruary 14# 1>J?# (ell*s patentapplication was file$ by his attorney. %t came only hours before lisha Cray file$ his =otice of%nvention for a telephone.

Mystery still surroun$s (ell*s application an$ what happene$ that $ay. %n particular# the "ey pointto (ell*s application# the principle of variable resistance# was scrawle$ in a margin# almost as an

afterthought. Some thin" (ell was tol$ of Cray*s =otice then allowe$ to change his application.That was never prove$# $espite some ?


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(ell*s patent# I.S. =umber 1J4#4?# has been calle$ the most valuable ever issue$. %f you haveXuic"Time or another way to view .tif files you can view the $ocument at theInite$ States9atent an$ Tra$emar" site 0e'ternal lin".Search for it by the number. ach page of the si' page$ocument is about 23


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permanent magnets pro$uce$.

%t was not until 1>>2# with the intro$uction of the (la"e transmitter# that (ell telephones onceagain use$ line power. The so calle$ local battery circuit use$ a battery supplie$ at the phone topower the line an$ ta"e speech to the local switch. Aoice powere$ phones $i$ not go away

completely# as some systems continue$ to be use$ for critical applications# those which may havebeen threatene$ by spar". %n 1E?4 =&S& use$ a voice powere$ system $escribe$ as follows:

D& networ" of 24 channels with a total of more than 4< soun$ powere$ telephones# which $erivetheir power solely from the human voice# provi$e the communications between the ast &reacentral bloc"house 0left an$ the various test stan$s at =&S&*s Ceorge ). Marshall Space light)enter here. . .D The complete article is here:http:americanhistory.si.e$uscienceservice


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telephone system. !ue to limite$ space % can cover only some maor =orth &merican events. ,fthese# the two most important $evelopments were the invention of the vacuum tube an$ thetransistorO to$ay*s telephone system coul$ not have been built without them.

9rogress came slowly after the original invention. (ell an$ +atson wor"e$ constantly onimproving the telphone*s range. They ma$e their longest call to $ate on ,ctober E# 1>J?. %t was a$istance of only two miles# but they were so overoye$ that later that night they celebrate$# $oingso much began $ancing that their lan$la$y threatene$ to throw them out. +atson later recalle$

D(ell . . . ha$ a habit of celebrating by what he calle$ a war $ance an$ % ha$ got so e'pose$ at itthat % coul$ $o it 8uite as well as he coul$.D +atsonU The rest of 1>J?# though# was $ifficult for(ell an$ his bac"ers.

(ell an$ +atson improve$ the telephone an$ ma$e better mo$els of it# but these changes weren*tenough to turn the telephone from a curiosity into a nee$e$ appliance. 9romoting an$ $evelopingthe telephone prove$ far har$er than ubbar$# San$ers# or (ell e'pecte$. =o switchboar$se'iste$ yet# the telephones were in$ee$ cru$e an$ transmission 8uality was poor. Many8uestione$ why anyone nee$e$ a telephone. &n$ $espite (ell*s patent# broa$ly covering the entiresubect of transmitting speech electrically# many companies sprang up to sell telephones an$telephone service. %n a$$ition# other people file$ applications for telephones an$ transmitters after

(ell*s patent was issue$. Most claime$ (ell*s patent coul$n*t pro$uce a wor"ing telephone or thatthey ha$ a prior claim. 7itigation loome$. earing financial collapse# ubbar$ an$ San$ersoffere$ in the fall of 1>J? to sell their telephone patent rights to +estern Inion for W1


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)lic" here for a short but nice history 0internal lin"

,n &pril 2J# 1>JJ Thomas $ison file$ a patent application for an improve$ transmitter# a $evicethat ma$e the telephone practical. & maor accomplishment# $ison*s patent claim was $eclare$in interference to a =otice of %nvention for a transmitter file$ ust two wee"s before by mile(erliner. This conflict was not resolve$ until 1>>? however# $ison $eci$e$ to pro$uce thetransmitter while the matter was $ispute$. 9ro$uction began towar$ the en$ of 1>JJ. To compete#(ell soon incorporate$ in their phones an improve$ transmitter invente$ by rancis (la"e.

(la"e*s transmitter relie$ on the $iaphragm mo$ifying an e'isting electrical current# an outsi$epower source. This was 8uite $ifferent than the original invention an$ its improvements. (ell*sfirst telephone transmitter use$ the human voice to generate a wea" electro/magnetic fiel$# whichthen went to a $istant receiver. (ell later installe$ larger# better magnets into his telephones butthere was a limit to what power the human voice coul$ provi$e# Myer in$icating about 1JJ San$ers# ubbar$# an$ (ell forme$ the first (ell telephone company. achassigne$ their rights un$er four basic patents to ubbar$*s trusteeship. &gainst tough criticism#ubbar$ $eci$e$ to lease telephones an$ license franchises# instea$ of selling them. This ha$enormous conse8uences. %nstea$ of ma"ing money 8uic"ly# $ollars woul$ flow in over months#years# an$ $eca$es. 9ro$ucts were also affecte$# as a lease arrangement meant telephones nee$e$to be of rental 8uality# with innovations intro$uce$ only when the e8uipment was virtually troublefree. %t prove$ a wise enough $ecision to sustain the (ell System for over a hun$re$ years.

%n September# 1>JJ +estern Inion change$ its min$ about telephony. They saw it woul$ wor"an$ they wante$ in# especially after a subsi$iary of theirs# the Col$ an$ Stoc" Telegraphy
http://www.privateline.com/TelephoneHistory2A/ericsson.htmhttp://www.privateline.com/TelephoneHistory2A/ericsson.htm


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)ompany# rippe$ out their telegraphs an$ starte$ using (ell telephones. Rather than buying patentrights or licenses from the (ell# +estern Inion $eci$e$ to buy patents from others an$ start theirown telephone company. They were not alone. &t least 1#J3< telephone companies organi-e$ an$operate$ in the 1J years (ell was suppose$ to have a monopoly.

Most competitors $isappeare$ as soon as the (ell )ompany file$ suit against them for patentinfringement# but many remaine$. They either $isagree$ with (ell*s right to the patent# ignore$ italtogether# or starte$ a phone company because (ell*s people woul$ not provi$e service to theirarea. %n any case# +estern Inion began entering agreements with Cray# $ison# an$ &mos .!olbear for their telephone inventions. %n !ecember# 1>JJ +estern Inion create$ the &mericanSpea"ing Telephone )ompany. & tremen$ous selling point for their telephones was $ison*simprove$ transmitter. (ell Telephone was $eeply worrie$ since they ha$ installe$ only 3#J># the worl$*s first telephone $irectory came out# a single paper of only fiftynames. Ceorge +illiar$ )oy an$ a group of investors in the =ew aven !istrict Telephone)ompany at 21E )hapel Street pro$uce$ it. %t was followe$ 8uic"ly by the listing pro$uce$ by theo$$ly name$ (oston Telephone !espatch )ompany. irst $irectoryU

%n 1>J> 9resi$ent Rutherfor$ (. ayes a$ministration installe$ the first telephone in the +hiteouse. irst teleU Mary inch oyt reports that the first outgoing call went to &le'an$er Craham(ell himself# thirteen miles $istant. ayes first wor$s instructe$ (ell to spea" more slowly.oytU

%n that year the (utterstamp telephone came into use. This telephone combine$ the receiver an$transmitter into one han$hel$ unit. @ou tal"e$ into one en$# turne$ the instrument roun$ an$listene$ to the other en$. 9eople got confuse$ with this clumsy arrangement# conse8uently# atelephone with a secon$ transmitter an$ receiver unit was $evelope$ in the same year. @ou coul$use either one to tal" or listen an$ you $i$n*t have to turn them aroun$. This wall set use$ a cran"to signal the operator.
http://www.privateline.com/Switching/EarlyWork.htmlhttp://www.privateline.com/Switching/EarlyWork.html


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The (utterstamp telephone.

or another great page on the earliest commercial telephones go here:

http:atcaonline.comphonein$e'.html 0e'ternal lin"

,n &ugust 1# 1>J> Thomas +atson file$ for a ringer patent. Similar to enry*s classroom$oorbell# a hammer operate$ by an electromagnet struc" two bells. Turning a cran" on the callingtelephone spun a magneto# pro$ucing an alternating or ringing current. 9reviously# people use$ acru$e thumper to signal the calle$ party# hoping someone woul$ be aroun$ to hear it. The ringerwas an imme$iate success. (ell himself became more optimistic about the telephone*s future#prophetically writing in 1>J> D% believe that in the future# wires will unite the hea$ offices of theTelephone )ompany in $ifferent cities# an$ that a man in one part of the country maycommunicate by wor$ of mouth with another in a $istant place.D

Subscribers# meanwhile# grew stea$ily but slowly. San$ers ha$ investe$ W11J># forming a new (ell Telephone )ompany as well as the =ew nglan$ Telephone)ompany# a forerunner of the strong regional (ell companies to come. 1


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patents. %t also retaine$ its telegraph business as before. This $ecision so enlarge$ =ational (ellthat a new entity with a new name# &merican (ell )ompany# was create$ on ebruary 2>>1. The ta"eover was consummate$ on ebruary 2?# 1>>2# with +estern lectricgiving up its remaining patent rights as well as agreeing to pro$uce pro$ucts e'clusively for&merican (ell. %t was not until 1>> that Aail woul$ form his long $istance telephone company.%t was calle$ &T6T.

,n uly 1E# 1>>1 (ell was grante$ a patent for the metallic circuit# the concept of two wiresconnecting each telephone. Intil that time a single iron wire connecte$ telephone subscribers#ust li"e a telegraph circuit. & conversation wor"s over one wire since groun$ing each en$provi$es a complete path for an electrical circuit. (ut houses# factories an$ the telegraph systemwere all groun$ing their electrical circuits using the same earth the telephone company employe$.& huge amount of static an$ noise was conse8uently intro$uce$ by using a groun$e$ circuit. &metallic circuit# on the other han$# use$ two wires to complete the electrical circuit# avoi$ing thegroun$ altogether an$ thus provi$ing a better soun$ing call.

The brilliant .. )arty intro$uce$ two wireservice commercially in ,ctober of that year on acircuit between (oston an$ 9rovi$ence. %t cut noise greatly over those forty five miles an$heral$e$ the beginning of long $istance service. Still# it was not until 1< years later that (ellstarte$ converting groun$e$ circuits to metallic ones

9ermalin"V )omments 0


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(efore continuing let*s loo" at Strowger*s achievement. The automatic $ial system# after all#change$ telephony forever. &lmon (rown Strowger 0pronounce$ STR,/er was born in 1>3E in9enfiel$# =ew @or"# a close suburb of Rochester. 7i"e (ell# Strowger was not a professionalinventor# but a man with a "een interest in things mechanical. Swihart says he went to ane'cellent =ew @or" State university# serve$ in the )ivil +ar from 1>?1 to 1>? 0en$ing as a

lieutenant# taught school in Lansas an$ ,hio afterwar$s# an$ woun$ up first in Tope"a an$ thenLansas )ity as an un$erta"er in 1>>?. This unli"ely profession of an inventor so inspire$ seemso$$ in$ee$# but the stories surroun$ing his motivation to invent the automatic switch are o$$erstill.

Than"s to oe ,ster for supplying Strowger*s birthplace

The many stories suggest# none of which % can confirm# that someone was stealing &lmonStrowger*s business. Telephone operators# perhaps in league with his competitors# were routingcalls to other un$erta"ers. These operators# suppose$ly# gave busy signals to customers callingStrowger or even $isconnecte$ their calls. Strowger thus invente$ a system to replace an operator

from han$ling local calls. %n the $istillation of these many stories# Stephan 7esher relates a storyfrom &lmon*s time in Tope"a:

D%n his boo"# Coo$ )onnections# telephone historian !ave 9ar" writes that Strowger grew $ar"lysuspicious when a close frien$ in Tope"a $ie$ an$ the man*s family $elivere$ the bo$y to a rivalmortician. Strowger conten$e$ that an operator at the new telephone e'change ha$ intentionally$irecte$ the call to a competitor // an allegation that gave rise to tales that the operator was eithermarrie$ to# or the $aughter of# a competing un$erta"er.D

Coo$ connections : & )entury of Service by the Men 6 +omen of Southwestern (ell by !avi$C. 9ar" 07ong out of print# but try htttp:www#abe.com

+hatever the circumstances# we $o "now that anti/(ell System sentiment ran high at this time#that goo$ telephone inventions comman$e$ rea$y money# an$ that Strowger $i$ have numerousproblems with his local telephone company. Strowger was a regular complainer an$ onecomplaint stan$s out.

Swihart $escribes how Southwestern (ell personnel were calle$ out to once again visitStrowger*s business# to fi' a $ea$ line. The cause turne$ out to be a hanging sign which flappe$in the bree-e against e'pose$ telephone contacts. This shorte$ the line. ,nce the sign wasremove$ the line wor"e$ again. %t may be suppose$ that this sort of problem was beyon$ acustomer*s ability to $iagnose# that Strowger ha$ a legitimate complaint. (ut on this occasionSouthwestern (ell*s assistant general manager# a one erman Ritterhoff# was along with therepair crew. Strowger invite$ the man insi$e an$ showe$ him a mo$el for an automatic switch.So Strowger was wor"ing on the problem for 8uite some time an$ was no novice to telephonetheory.

(roo"s says that# in fact# Strowger "new technology so well that he built his patent on (ellsystem inventions. %t must be pointe$ out# however# that every inventor $raws i$eas an$inspiration from previously $one wor". (roo"s says specifically that the )onnolly/McTighepatent 09atent number 222# 4># $ate$ !ecember E# 1>JE helpe$ Strowger# a faile$ $ial


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switchboar$# as well as an early automatic switch $evelope$ by r-a Cillilan$. (ut Strowger $i$not buil$ the instrument since he $i$ not have the mechanical s"ills. & rather clueless eweler wasemploye$ instea$ to buil$ the first mo$el# an$ much time was waste$ with this man# getting himto follow instructions.

&s with (ell# Strowger file$ his patent without having perfecte$ a wor"ing invention. @et he$escribe$ the switch in sufficient $etail an$ with enough novel points for it to be grante$ 9atentnumber 44J#E1># on March 1E1. &n$ in a further parallel with (ell# &lmon Strowger lostinterest in the $evice once he got it built. %t fell upon his brother# +alter S. Strowger# to carry$evelopment an$ promotion further# along with a great man# oseph arris# who also helpe$ withpromotion an$ investment money. +ithout arris# soon to be the organi-er an$ gui$ing forcebehin$ &utomatic lectric# $ial service may have ta"en $eca$es longer for the (ell System torecogni-e an$ $evelop. )ompetition by &.. force$ the (ell System to play switching catchup#something they really only accomplishe$ in the 1E4EJ Milo Ciffor$ Lellogg foun$e$ the Lellogg Switchboar$ an$ Supply )ompany near)hicago. Lellogg was a Dgra$uate engineer an$ accomplishe$ circuit $esignerD9leasanceU# whobegan his career in 1>J< with Cray an$ (arton# e8uipment manufacturers for +estern lectric.There he $evelope$ +estern lectric*s best telephone switchboar$s: a stan$ar$ mo$el an$ amultiple switchboar$. (oth were invente$ in 1>JE an$ patente$ in 1>>1 an$ 1>>4# respectively.e retire$ from +estern lectric in 1>># Dan$ began ma"ing an$ patenting a series of telephoneinventions of his own# which wor" e'ten$e$ over a perio$ of 12 years an$ which culminate$ inthe issue of 12 patents to him on ,ctober 1J# 1>EJ# besi$es which over 2 ha$ previously beenissue$ to him.DTelephonyU e was also 8uite political# successfully winning suits against (ellan$ $elaying other (ell actions to his benefit. Telecom istory calle$ him Dprobably the man inthe &merican in$epen$ent telephone business who first place$ himself in opposition to the (ell)ompany.DTelephonyU

is maor accomplishment was the so calle$ $ivi$e$/multiple switchboar$# of which two werebuilt. ,ne was sol$ to the )uyahoga Telephone )ompany of )levelan$# ,hio an$ the other to theLinloch Telephone company of Saint 7ouis. The )levelan$ installation boaste$ E#?


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@or" ha$ less restrictive corporate laws than Massachusetts. The &merican (ell Telephone)ompany name passe$ into history.

%n 1E.

!etails from the patent. )lic" to enlarge

%n 1E


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to the in$epen$ents for a year. &t that time the (ell System woul$ file a patent suit againstLellog# which they woul$ intentionally loose. This woul$ force the in$epen$ents to rip out theirnewly installe$ switchboar$s# crushing the largest in$epen$ents. The plan was $iscovere$#aborte$# an$ further scan$ali-e$ &T6T.Crosvenor2U

(y 1E


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Crosvenor2. ibi$# 1?J

(roo"s# ohn. Telephone: The irst un$re$ @ears. arper 6 Row# =ew @or". 1EJ# 1EJ?: 1


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& nice !e orest biography is at:http:www.acmi.net.au&%)!Q,RSTQ(%,.html 0e'ternal lin"The site also inclu$es the photograph below.

The most popular boo" on !e orest is mpire of the &ir : The Men +ho Ma$e Ra$io by Tom7ewis. Try searching for it with the 9owells.com search engine at the bottom of this page.

&T6T eventually bought his patent rights to use the tube in their telephone amplifier. ,nly afterthis an$ a year of inspecting !e orest*s e8uipment $i$ the (ell Telephone 7aboratory ma"e thetrio$e wor" for telephony. Those years of research were worth it. lectron tube base$ amplifierswoul$ ma"e possible ra$iotelephony# microwave transmission# ra$ar# television# an$ hun$re$s ofother technologies. Telephone repeaters coul$ now span the country# enabling a nationwi$etelephone system# fulfilling &le'an$er Craham (ell*s 1>J> vision.

Recalling those years in an important interview with the %# 7loy$ spenschie$ recounts D%nMay 1E


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& trio$e is sometimes calle$ a thermionic valve. Thermions are electrons $erive$ from a heate$source. & valve $escribes the tube*s properties: current flows in one $irection but not the other.Thin" of a faucet# a type of control valve# letting water go in only one $irection. This controlle$flow of electrons# not ust electricity itself# mar"s the en$ of the electrical age an$ the beginningof the electronic age.

Co here for more on $e orest an$ how the trio$e wor"s 0internal lin"

or more comments# rea$ Ray Strac"bein*s comments below

&rmstrong later $evelope$ the regenerative circuit which fe$ bac" the input signal into the circuitover an$ over again. %n electronic boo"s of the era many calle$ him Dee$bac" &rmstrong.D iscircuit amplifie$ the signal far more than original $esigns# allowing great wireless or wirelinetransmission signal strength. The fee$bac" circuit coul$ also be over$riven# fe$ bac" so manytimes that supplying a small current woul$ $evelop an e'tremely high fre8uency. The circuitwoul$ thus resonate at the fre8uency of a ra$io wave# letting the trio$e receive or $etect signals#

not ust transmit them. !eorest later claime$ to have invente$ regenerationO this was a lie.!eorest invente$ the three element tube by trial an$ errorO he $i$ not even un$erstan$ how itwor"e$ until five years later when $win &rmstrong e'plaine$ it.

More on this regar$ing ra$io is here 0internal lin"

&s evi$ence of the trio$e*s success# on anuary 2# 1E1 the first transcontinental telephone lineopene$ between =ew @or" )ity an$ San rancisco. The previous long $istance limit was =ew@or" to !enver# an$ only then with some shouting. Two metallic circuits ma$e up the lineO it use$2#


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worl$. %t became the secon$ largest telecommunications manufacturer in the Inite$ States after+estern lectric.D

inally# on =ovember ># 1E1E# in what must have been a humiliating e'perience for thetelecommunications giant# &T6T at last intro$uce$ large scale automatic switching e8uipment to

their telephone system. Ising step by step e8uipment ma$e# bought# an$ installe$ by &utomaticlectric. The cut over to $ial in =orfol"# Airginia was a complete (ell System policy change. =olonger woul$ they convert automatic $ial systems to manual as they bought in$epen$enttelephone companies# but they woul$ instea$ embrace step by step e8uipment an$ install more.

More on the many mergers of &utomatic lectric is here

%n 1E21 the (ell System intro$uce$ the first commercial panel switch# a very o$$ invention.!evelope$ over eight years# it was &T6T*s response to the automatic $ialing feature offere$ bystep by step e8uipment. %t offere$ many innovations an$ many problems. &lthough customerscoul$ $ial out themselves# the number of parts an$ its operating metho$ ma$e it noisy for callers.%ronically# some switchmen say it was a 8uiet machine insi$e the central office# emanating Dacollection of simply $elightful *clin"ing#* *whirring* an$ *s8uea"# s8uea"# s8uea"* noises.D +or"ingli"e a game of Sna"es an$ 7a$$ers# the switch use$ selectors to connect calls# these mechanicalarms moving up an$ $own in large ban"s of contacts. +hen crossbar switching came on thescene in 1E3># panel switches were remove$ where possible# although some remaine$ wor"inguntil the mi$ 1EJ


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http:www.ieee.orgorgani-ationshistoryQcenteroralQhistoriestranscriptssears.html 0e'ternallin"



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1E2E# when the 'ecutive ,ffices were remo$ele$ the historic one/position switchboar$ whichha$ serve$ for so many years was retire$ from service an$ a new two/position switchboar$#especially built to meet the 9resi$ent*s nee$s# was installe$. The number of stations wasmaterially increase$ in a$$ition to many special circuits for the use of the 9resi$ent. %t was at thistime a telephone was installe$ on the 9resi$ent*s $es" for the first time.D oover 7ibraryU

0Than"s to 7. =ic"el for researching this point

The Inite$ States )ongress create$ the e$eral )ommunications )ommission in 1E34 to regulatetelephones# ra$io# an$ television. %t was part of 9resi$ent Roosevelt*s D=ew !ealD plan to bring&merica out of the Creat !epression. =ot content to merely follow congressional $ictates# an$unfortunately for wireless users# the agency first thought it shoul$ promote social change throughwhat it $i$. To promote the greater goo$ with ra$io# the .).). gave priority to emergencyservices# broa$casters# government agencies# utility companies# an$ other groups it thoughtserve$ the most people while using the least ra$io spectrum. This meant few channels for ra$io/telephones since a single wireless call uses the same ban$wi$th as an .M. ra$io broa$cast

stationO large fre8uency bloc"s to serve ust a few people.

Treating ra$io li"e a public utility# something li"e the railroa$s# it was thought a public agencycoul$ protect the public against monopoly practices an$ price gouging. (ut li"e manybureaucracies# at every opportunity the )) trie$ to enlarge its role an$ power# eventuallyaligning itself with large communications companies an$ then actually wor"ing against theconsumer. The worst e'amples were outsi$e of telephony# helping the R)& corporation against.M. broa$casting# ruining $win &rmstrong in the process# an$ favoring R)& over arnsworth#the first real $eveloper of television# leaving him penniless as well. &long the way werema$$ening $elays in approving technical a$vances an$ fre8uency allocations# something thatcontinues to this $ay.

7ate in 1E34 the )) began investigating &T6T as well as every other telephone company. The)) issue$ a *9ropose$ Report* after four years# in which its commissioner e'coriate$ &T6T for#among other things# unustifiable prices on basic phone service. The commissioner also urge$ thegovernment to regulate prices the (ell System pai$ +estern lectric for e8uipment# in$ee$# evensuggesting &T6T shoul$ let other companies bi$ on +estern lectric wor". The (ell Systemcountere$ each point of the ))*s report in their 1E3> &nnual Report# however# it was clear thegovernment was now closely loo"ing at whether the (ell System*s structure was goo$ for&merica. &t that time &T6T controlle$ >3 percent of Inite$ States telephones# E1 percent oftelephone plant an$ E> percent of long $istance lines. ,nly the outbrea" of +orl$ +ar %%# two an$a half months after the final report was issue$ in 1E3E# stave$ off close government scrutiny.

%n 1E3J &lec Reeves of (ritain invente$ mo$ern $igital transmission when he $evelope$ 9ulse)o$e Mo$ulation. % say mo$ern because Morse co$e an$ its variants are also $igital: organi-e$on an$ off pulses of electrical energy that convey information. +hile 9)M too" $eca$es toimplement# the a$vent of $igital wor"ing was a momentous event an$ $eserves muchconsi$eration. !avi$ Robertson# a biographer of Reeves# goes so far as to claim Reeves as thefather of mo$ern telecommunications. D% thin" a fair argument can be sustaine$ that the a$optionof $igital is the principal motor of change in the early 21st century. or sure# there*$ have been nomerger between &,7 an$ Time +arner an$ other moves towar$s combining me$ia with telecom
http://www.privateline.com/PCS/Digiprinc.htmhttp://www.privateline.com/PCS/Digiprinc.htmhttp://www.privateline.com/PCS/Digiprinc.htmhttp://www.privateline.com/PCS/Digiprinc.htm


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companies ha$ it not become possible to transmit information of all sorts in the same binary way.+hether all this is goo$ news is# of course# another issue.D

or more information on &lec Reeves clic" here 0internal lin"

or a website $evote$ to Reeves go here:http:www.&lecarleyReeves.com 0e'ternal lin"

%n 1E3J coa'ial cable was installe$ between Tole$o# ,hio an$ South (en$# %n$iana. 7ong$istance lines began moving un$ergroun$# a big change from overhea$ lines carrie$ on poles. %nthat same year the first commercial messages using carrier techni8ues were sent through the coa'#base$ on transmission techni8ues invente$ by 7loy$ spenschie$ an$ erman &. &ffel.Multiple'ing let toll circuits carry several calls over one cable simultaneously. %t was sosuccessful that by the mi$ 1E at 3#>3>#


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& little bit on ra$ar $evelopment in +orl$ +ar %%

(ac" to crossbar. =ote the watch/li"e comple'ity in the $iagram. )urrent moving through theswitch move$ these electro/mechanical relays bac" an$ forth# $epen$ing on the $ial pulsesreceive$. !espite its beauty# these switches were bul"y# complicate$ an$ costly. The ne't

invention we loo" at woul$ in time sweep all manual an$ electro/mechanical switching away.

///////////////////////////////////////////

Resources

(7RU DThe ,pening of Transatlantic Service on ShortwavesD ? (ell 7aboratories Recor$ 1E2>:4


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,n uly 1# 1E4> the (ell System unveile$ the transistor# a oint invention of (ell 7aboratoriesscientists +illiam Shoc"ley# ohn (ar$een# an$ +alter (rattain. %t woul$ revolutioni-e everyaspect of the telephone in$ustry an$ all of communications. ,ne engineer remar"e$# D&s"ing usto pre$ict what transistors will $o is li"e as"ing the man who first put wheels on an o' cart toforesee the automobile# the wristwatch# or the high spee$ generator.D ,thers were less restraine$.

%n 1E4# recently retire$ )hief of ngineering for &T6T# !r. arol$ ,sborne# pre$icte$# D7et ussay that in the ultimate# whenever a baby is born anywhere in the worl$# he is given at birth anumber which will be his telephone number for life. &s soon as he can tal"# he is given awatchli"e $evice with 1< little buttons on one si$e an$ a screen on the other. Thus e8uippe$# atany time when he wishes to tal" with anyone in the worl$# he will pull out the $evice an$ punchon the "eys the number of his frien$. Then turning the $evice over# he will hear the voice of hisfrien$ an$ see his face on the screen# in color an$ in three $imensions. %f he $oes not see an$ hearhim he will "now that the frien$ is $ea$.D )onlyUSheesh.

The first transistor loo"ing as cru$e# perhaps# as the first telephone. The point contact transistorpicture$ here is now obsolete.


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)apitali-ing on a flowing stream of electrons# along with the special characteristics of silicon an$germanium# the transistor was built into amplifiers an$ switching e8uipment. earing ai$s#ra$ios# phonographs# computers# electronic telephone switching e8uipment# satellites an$ moonroc"ets woul$ all be improve$ or ma$e possible because of the transistor. 7et*s $epart again fromthe narrative to see how a transistor wor"s.

Transistor stan$s for transit resistor# the temporary name# now permanent# that the inventors gaveit. These semi$con$uctors control the electrical current flowing between two terminals byapplying voltage to a thir$ terminal. @ou now have a minature switch# presenting either a freewayto electrons or a bric" wall to them# $epen$ing on whether a signal voltage e'ists. (ul"ymechanical relays that use$ to switch calls# li"e the crossbar shown above# coul$ now be replace$with transistors. There*s more.

Transistors amplify when built into a proper circuit. & wea" signal can be booste$ tremen$ously.7et*s say you have ten watts flowing into one si$e of the transistor. @our current stops becausesilicon normally isn*t a goo$ con$ucter. @ou now intro$uce a signal into the mi$$le of the

transistor# say# at one watt. That changes the transistor*s internal crystalline structure# causing thesilicon to go from an insulator to a con$uctor. %t now allows the larger current to go through#pic"ing up your wea" signal along the way# impressing it on the larger voltage. @our one wattsignal is now a ten watt signal.

Transistors use the properties of semi/con$uctors# seemingly innocuous materials li"e geraniuman$ now mostly silicon. Materials li"e silver an$ copper con$uct electricity well. Rubber an$porcelain con$uct electricity poorly. The $ifference between electrical con$uctors an$ insulatorsis their molecular structure# the stuff that ma"es them up. +eight# si-e# or shape $oesn*t matter#it*s how tightly the material hol$s on to its electrons# preventing them from freely flowingthrough its atoms.

Silicon by itself is an or$inary element# a common part of san$. %f you intro$uce impurities li"earsenic or boron# though# you can turn it into a con$uctor with the right electrical charge.Selectively placing precise impurities into a silicon chip pro$uces an electronic circuit. %t*s li"ema"ing a magnetically polari-e$# multi/layere$ chemical ca"e. Aary the ingre$ients or elementsan$ you can ma"e up many "in$s of ca"es or transistors. &n$ each will taste or operate a little$ifferently.

&s %*ve ust hinte$# there are many "in$s of transistors# ust as there are many $ifferent "in$s oftubes. %t*s the trio$e*s soli$ state e8uivalent: the fiel$ effect transistor or T. The T we*ll loo"at goes by an intimi$ating name# M,ST for Metal ,'i$e Semicon$uctor iel$ ffectTransistor. +hew That*s a big name but it $escribes what it $oes: a metal toppe$ $evice wor"ingby a phenomenon calle$ a fiel$ effect.

& silicon chip ma"es up the T. Three separate wires are wel$e$ into $ifferent parts. Theseelectro$e wires con$uct electricity. The source wire ta"es current in an$ the $rain wire ta"escurrent out. & thir$ wire is wire$ into the top. %n our e'ample the silicon wafer is positivelycharge$. urther# the manufacturer ma"es the areas hol$ing the source an$ $rain negative. Thesetwo negative areas are thus surroun$e$ by a positive.


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& much more accurate transistor e'planation here

=ow we intro$uce our wea" signal current# say a telephone call that nee$s amplifying. The circuitis so arrange$ that its current is positive. %t goes into the gate where it pushes against the positivecharge of the silicon chip. That*s li"e two positive magnets pushing against each other. %f you*veever trie$ to hol$ two li"e magnets together you "now it*s har$ to $o // there*s always a spacebetween them. Similarly# a signal voltage pushing against the chip*s positive charge gives spaceto let the current go from the source to the $rain. %t pic"s up the signal along the way. )hec" outthis $iagram# mo$ifie$ only slightly from 7ucent*s e'cellent site:

http:www.lucent.commin$stransistortech.html

&s 7ouis (loomfiel$ of Airginia puts it:DThe M,ST goes from being an insulating $evicewhen there is no charge on the gate to a con$uctor when there is charge on the gate This propertyallows M,STs to amplify signals an$ control the movements of electric charge# which is why

M,STs are so useful in electronic $evices such as stereos# televisions# an$ computers.D

% "now that this is a simple e'planation to a forbi$$ingly $ifficult topic# but % thin" it*s enough fora history article. Than"s to &ustralia*s ohn +ong for help with his section. %f you*$ li"e to rea$further# chec" out 7ucent*s transistor page by searching their site: http:www.lucent.com0e'ternal lin"
http://www.privateline.com/transistor/index.htmlhttp://www.lucent.com/minds/transistor/tech.htmlhttp://www.lucent.com/http://www.lucent.com/http://www.privateline.com/transistor/index.htmlhttp://www.privateline.com/transistor/index.htmlhttp://www.lucent.com/minds/transistor/tech.htmlhttp://www.lucent.com/http://www.lucent.com/


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%f you have a better e'planation or something to a$$#please contact me&n$ now bac" to thenarrative.



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(ut what about crossing the seasP Microwave wasn*t possible over the ocean an$ ra$iotelephonywas limite$. @ears of $evelopment lea$ up to 1E? when the first transatlantic telephone cablesystem starte$ carrying calls. %t cost 42 million $ollars. Two coa'ial cables about 2< miles apartcarrie$ 3? two way circuits. =early fifty sophisticate$ repeaters were space$ from ten to fortymiles along the way. ach vacuum tube repeater containe$ #


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&T6T was responsible for their new attitu$e. ,n &ugust E# 1E1 %TT began buying Lelloggstoc"# eventually ac8uiring the company. %n 1E2 the Lellogg Switchboar$ an$ Supply companypasse$ into history# merging with %TT.

Roger )on"lin relates# D%n ust a few years after the buyout# %TT change$ the name from Lellogg

Switchboar$ 6 Supply )ompany to %TT Lellogg. Then# after merging e$eral Telephone an$Ra$io )orporation# its separate telephone manufacturing company in )lifton# =. into %TTLellogg an$ combining manufacturing operations into its )icero &ve. facility in )hicago# thename was change$ again to %TT Telecommunications. . . . The last change to %TTTelecommunications too"U place inU1E?3.D

D%n 1E>E# %TT sol$ its entire worl$wi$e telecommunications pro$ucts business to &lcatel an$with$rew totally from this business. %n 1EE2 &lcatel sol$ what ha$ formerly been %TT*s customerpremises e8uipment 0)9 business in the IS# inclu$ing its factory in )orinth# MS. to a group ofprivate investors hea$e$ by !avi$ 7ee. %nitially after purchasing this business from &lcatel# thisnew company was "nown as )ortelco Lellogg. %t continues to manufacture an$ mar"et what ha$

formerly been %TT*s I.S./ma$e telephones an$ relate$ pro$ucts. The name *Lellogg* has sincebeen $roppe$ from its name an$ the company is now "nown as )ortelco. or a short while)ortelco continue$ to use the %TT name an$ tra$emar" on its pro$ucts un$er a license from %TT#but this also has been $iscontinue$.DThe %TT information above came from the e'cellent history site http:www.sigtel.com 0e'ternallin"# now $ea$# pro$uce$ by the I.L.*s &n$rew mmerson# a first ran" telephone historian.

%n 1E2 the (ell System began increasing payphone charges from a nic"el to a $ime. agenU %twasn*t an imme$iate change since both the payphone an$ the central office switching e8uipmentthat service$ it ha$ to be mo$ifie$. (y the late 1E2#


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years earlier in 1E< / 7eich lectric. (ut the a$$ition of &*s engineering an$ manufacturingcapacity assure$ CT of e8uipment for their rapi$ly growing telephone operations.

&n e'cellent timeline on &utomatic lectric history is at the &C)S site. The D&D in the namestan$s for &T6T# the DCD for DCTD. !ivisions from both companies combine$ in 1E>E to form

&C)S:http:www.agcs.com 0e'ternal lin"

Ceneral was foun$e$ in 1E2? as &ssociate$ Telephone Itilities bySigur$ ,$egar$. The companywent ban"rupt $uring the Creat !epression an$ in 1E34 reorgani-e$ itself as Ceneral Telephone.Ceneral ha$ its own manufacturing company# 7eich lectric# which began in 1E


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%n 1E?3 the first mo$ern touch/tone phone was intro$uce$# the +estern lectric 1


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switch prove$ a success but there were some problems for (ell 7abs engineers# particularly whena =o.1SS became overloa$e$. %n those circumstances it ten$e$ to fail all at once# rather thanbrea"ing $own bit by bit.

///////////////////////////////////

Resources

MyersU Myer# Ralph ,# 1EE# ,l$ Time Telephones: Technology# Restoration an$ Repair# Tab(oo"s# =ew @or". 123 'cellent.

Swihart# StanleyU Telecom istory: The ournal of the Telephone istory %nstitute# %ssue 2#Spring 1EE

TU vents in Telecommunication istory# 1EE2 #&T6T &rchives 9ublication 0>.E2/2M# p3

(ell 7aboratories Recor$U D)oast to )oast Ra$io Relay System ,pens.D (ell 7aboratoriesRecor$# May# 1E1. 42J

(ell 7aboratories Recor$U +eber# ).&.# ac"ete$ )or$s for Telephones# (ell 7aboratoriesRecor$# May# 1EE 1>J

agenU agen# M.!.# e$. & istory of ngineering an$ Science in the (ell System: Aolume 1The arly @ears# 1>J /1E2. =ew @or": (ell Telephone 7aboratories# 1EJ# 3J (rieflymentions coin services.

+illiam Myre $iscussion on interchangeable partsU

&s a teenager in the ?


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The electrical $ifferences# if they e'ist# woul$ have to be in the microphone# spea"er# or capacitoruse$ in series with the ringer coil 0an$ the coil impe$ance.

% $on*t remember if the same color co$ing was use$ on the internal wiring# but % can certainly saythat having a + phone to e'amine $i$ not help me re/wire the insi$e of an & phone that ha$

been unwire$.

% still have a "eye$ & phone in my garage. % also somewhere probably still have the technicalbulletin & sent me to rewire the & phone.

+illiam Myre



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was calle$ the =o. 1 &B 0lectronic &utomatic 'change. Crowth wasn*t han$le$ well#though# by their parent company# Ceneral Telephone an$ lectronics.

CT was then a poorly manage$ conglomerate of 23 regional phone companies an$ a ma"er of#among other things# televisions an$ light bulbs. They ha$ their successes an$ failures. ,ne

notable achievement is below.

D%ntro$ucing a crimestopper so a$vance$ !ic" Tracy $oesn*t have it yet.D

%n1EJ1 Ceneral Telephone an$ lectronics 0CT Sylvania intro$uce$ a $ata system calle$

!igicom. %t let $ispatchers i$entifying patrol car locations on a screen# an$ allowe$ officers to runlicense plate chec"s. +hen a patrolman touche$ a spot on the $igicom screen it lit up the samespot on the $ispatcher*s map. 9ro$uce$ by their Sociosystems 9ro$ucts ,rgani-ation# % $o not"now how many units were actually installe$ by CT# but it certainly foresha$owe$ later$evelopments. To$ay many police $epartments use cellular $igital pac"et $ata 0)!9! to runplates an$ communicate in te't with their $ispatchers. )!9! runs on e'isting cellular networ"s#with $ata rates no more that E.? or 1E.2 Lbs# a$e8uate for most purposes but slow when youconsi$er that in the year 2


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$imes. or some time now# we*ve been paying a healthy *phone bill* ourselves trying to ma"e ourservice $o everything you e'pect of it . . . !uring the ne't five years we*ll be spen$ing over W?billion upgra$ing an$ e'pan$ing every phase of our phone operation . . . 7a$ies an$ gentlemen#we*re wor"ing as fast as brains# manpower an$ money can combine to ma"e our service asefficient as possible.D

&n$ although CT might not have Dsat aroun$ counting $imes#D CT*s poor service recor$continue$# a reputation that haunts it to this $ay. Rightly or wrongly# the phone companies#particularly those in the (ell System# watche$ agog as customer relations got worse. ac"ing an$toll frau$ increase$ $ramatically# as the phone company became fair game# a soulless an$uncaring monster to war against. &ttac"ing Ma (ell became common an$ almost fashionable.

1EJ2 Ma$ Maga-ine cartoon. The caption rea$s: DStoc"hol$ers Crow &T &s Telephone IsersCo Ma$ &s Rates Rise &n$ Service lops.D

%n 1EJ4 the ustice !epartment began investigating &T6T again for violating antitrust laws. Theyrecommen$e$ +estern lectric an$ 7ong 7ines be $iveste$ from &T6T. Many people in usticeas well as throughout the country were concerne$ with the si-e of &T6T an$ their monopolystatus. &lthough everyone "new the (ell System provi$e$ the best telephone service in the worl$#it ha$ $one so with little or no competition. &T6T*s assets stoo$ at J billion $ollars. (ig was notgoo$ in the early 1EJ


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7ittle "nown outsi$e the in$ustry# the Stromberg/)arlson B/@ step by step switch soli$lycompete$ for business against Strowger technology 0manufacture$ by &utomatic lectric an$others in thousan$s of installations throughout rural &merica. Some may remain in Me'ico an$South &merica. &lthough the (ell System an$ many in$epen$ents preferre$ the Strowger $esignfor small communities# many telephone companies $i$ not. Strowger e8uipment often wor"e$

reliably for $eca$es but it was more complicate$ than B/@s an$ it re8uire$ a great $eal ofpreventative maintenance performe$ by s"ille$ craft wor"ers. Ray Strac"bein# who use$ to wor"for Stromberg/)arlson# says that B/@s# by comparison# nee$e$ few repairs an$ fi'es were simple.e writes# D% once met a husban$/an$/wife team that travele$ throughout the Creat 9lains in their+innebago motor home on a yearly cycle an$ routine$ hun$re$s of B/@ offices each year. Theywoul$ wor" &ri-ona# =ew Me'ico# an$ Te'as in the winter# an$ Montana# +yoming# an$ =orth!a"ota in the summer. ven a Switchman who coul$ not figure out how to wire a $oorbell for acentral office coul$ maintain a ).,. full of B/@ switches.D

Ray then goes on to $escribe the Stromberg/)arlson B/@ step by step switch# which coul$ beconfigure$ or enlarge$ in bloc"s of 1


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9lease visit Ray Strac"bien*s site 0e'ternal lin"

Stromberg/)arlson intro$uce$ their first $igital switch aroun$ 1EJ># the Stromberg )arlsonSystem )entury $igital switch.

&s switches were going $igital# so# too# were nearly all electronics in the telecommunicationfiel$. Still# a few technological hol$outs remaine$# as the (ell System replace$ their last localcor$ switchboar$ in 1EJ># on Santa )atalina %slan$ near the coast of 7os &ngeles# )alifornia.That*s right# operators still placing calls by han$ in the &ge of !isco. DTUhe smallest version of+estern*s 1?< toll switchboar$D was replace$ by a 3SS# the first (ell switch# inci$entally# to beshippe$ by barge. The city serve$ woul$ have been &valon. This accor$ing accor$ing to the une#1EJ> (ell 7aboratories Recor$ an$ personal correspon$ence with 9. gly of Santa Rosa#

)alifornia.

gly relates the following about &valon:

DTom# &valon ha$ its own inwar$ operator an$ % even remember the route# 213 K


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$ial service# since the magneto phones were 8uite elegant. . . all polishe$ woo$ an$ gleamingbrass bells. They were part of the perio$ atmosphere of the town.D

This simple switching technology came within si' years of outliving the most a$vance$telephone company on earth. (ut one manual local toll boar$ remaine$ in the public switche$

telephone networ" even longer.

.R. Sny$er r. remin$s us that toll boar$s# manual long $istance switches 0internal lin" to article#were still wor"ing in the (ell System after the last local plug boar$ was remove$.

//////////////////////////////

Resources

Strac"beinU 9ersonal correspon$ence with Tom arley# uly 1?# 2


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Michael athaway reports that DMyU parents owne$ the (ryant 9on$ Telephone )ompany in(ryant 9on$# Maine# the last han$/cran" magneto company to go $ial. %t was in our living rooman$ the last call was ma$e ,ctober 11# 1E>3.D an$ cran" magneto switchboar$s evolve$ aroun$the turn of the century. Their arrangement was not common battery# where the e'change orcentral office powers their e8uipment an$ supplies electricity to customer*s phones. Rather# as we

saw earlier in this series# a cran" at the switchboar$ operators position was turne$ to signal acustomer. Turn the cran" an$ you cause$ a $ial at a customer*s telephone to ring# a magneto in thecran" generating the ringing current. To place a call a customer signale$ the operator with asimiliar cran" on their telephone. & big battery in the base of the customer*s telephone supplie$the tal"ing power when a call got connecte$. This system is calle$ local battery# where thecustomer*s phone supplies the power. ere*s an e'ample of a magneto switchboar$ below# a 1E14+estern lectric Type 12


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actually written a boo" about the (ryant 9on$ Telephone )ompany calle$ *verything appene$&roun$ The Switchboar$.* %t*s 0obviously a story of family life aroun$ the switchboar$ an$ islight rea$ing with hopefully humor an$ nostalgia. % have lots of copies left an$ sell it $irectly. Thea$$ress is Mi"e athaway# 9, (o' J. (ut it is also available from9honecoinc.com# an$ several boo"stores.D

This site has a great list of en$ing $ates in telephonic history:http:www.sigtel.comtelQhistQlasts.html

To sum up# although some manual switchboar$s may have remaine$ in the 9ST=# those beingsmall office switches# or 9(Bs# the (ryant 9on$ boar$ was the last central office manuale'change in &merica. ,n this happy an$ nostalgic note of technology passing away# so at thesame time was the worl$*s greatest telephone company coming to an en$.

&lthough they ha$ pioneere$ much of telecom# many people though the information age wasgrowing faster than the (ell System coul$ "eep up. Many thought &T6T now stoo$ in the way of

$evelopment#

9ermalin"V )omments 04# the +estern lectric )ompany# then ol$er than the telephone itself# cease$to e'ist 0ochheiser 1EE1# 143. ,n that $ay of court or$ere$ $ivestiture# the (ell System wasbro"en into seven regional operating companies 0the (aby (ells an$ a more compact &T6T.&T6T retaine$ the long/$istance part of the business# its venerable research organi-ation 0(ell7aboratories# an$ its manufacturing operations 0which coul$ no longer have e'clusive supply

arrangements with the operating companies. & newly create$ &T6T Technologies# %nc. assume$the corporate charter of +estern lectric an$ continue$ ma"ing 1>0J1J/JE4/21E1 0J1J/JE4/21


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@ester$ay % brought home a battere$ an$ rotten woo$en crate % foun$ outsi$e a secon$ han$ store.% say outsi$e because it was in such ba$ shape that not even the thrift store thought it saleable#they $iscar$e$ it instea$. ar$ly fit as even a gar$en planter# % brought this oily an$ bro"en bo'home because of two wor$s stencile$ in three inch letters on the lengthwise si$es: +esternlectric. Cone are the rope han$le

The Subscriber Telephone Set

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Transcript of The Subscriber Telephone Set