 an impedance matching transformer to make it compatible with the impedance of the line. The Edison patents kept the Bell monopoly viable into the 20th century, by which time the network was more important than the instrument.

Early telephones were locally powered, using either a dynamic transmitter or by the powering of a transmitter with a local battery. One of the jobs of outside plant personnel was to visit each telephone periodically to inspect the battery. During the 20th century, telephones powered from the telephone exchange over the same wires that carried the voice signals became common.

Early telephones used a single wire for the subscriber's line, with ground return used to complete the circuit (as used in telegraphs). The earliest dynamic telephones also had only one port opening for sound, with the user alternately listening and speaking (or rather, shouting) into the same hole. Sometimes the instruments were operated in pairs at each end, making conversation more convenient but also more expensive.

At first, the benefits of a telephone exchange were not exploited. Instead telephones were leased in pairs to a subscriber, who had to arrange for a telegraph contractor to construct a line between them, for example between a home and a shop. Users who wanted the ability to speak to several different locations would need to obtain and set up three or four pairs of telephones. Western Union, already using telegraph exchanges, quickly extended the principle to its telephones in New York City and San Francisco, and Bell was not slow in appreciating the potential.

Signalling began in an appropriately primitive manner. The user alerted the other end, or the exchange operator, by whistling into the transmitter. Exchange operation soon resulted in telephones being equipped with a bell in a ringer box, first operated over a second wire, and later over the same wire, but with a condenser (capacitor) in series with the bell coil to allow the AC ringer signal through while still blocking DC (keeping the phone "on hook"). Telephones connected to the earliest Strowger switch automatic exchanges had seven wires, one for the knife switch, one for each telegraph key, one for the bell, one for the push-button and two for speaking. Large wall telephones in the early 20th century usually incorporated the bell, and separate bell boxes for desk phones dwindled away in the middle of the century.

Rural and other telephones that were not on a common battery exchange had a magneto hand-cranked generator to produce
an impedance matching transformer to make it compatible with the impedance of the course. The Edison patent kept the Bell monopoly viable into the 20th hundred, by which time the network was more important than the legal document. 

 Early telephones were locally powered, use either a dynamic transmitter or by the powering of a vector with a local battery. One of the jobs of outdoor plant force was to visit each telephone periodically to inspect the battery. During the 20th hundred, telephones powered from the telephone exchange over the like wires that carried the voice signals became coarse. 

 Early telephones used a single wire for the subscriber's line, with flat coat return used to complete the circuit (as used in telegraphs). The earliest dynamic telephones also had only one port opening for sound, with the user alternately listening and talk (or rather, shouting) into the like fix. Sometimes the instrument were operated in pairs at each end, making conversation more convenient but also more expensive. 

 At first, the benefit of a telephone exchange were not exploited. Instead telephones were leased in pairs to a subscriber, who accept to arrange for a telegraph contractor to construct a line between them, for case between a home and a workshop. Users who wanted the ability to speak to several different localization would need to obtain and set up three or four pair of telephones. Western Union, already using telegraph exchanges, quickly gallop the rationale to its telephones in New York City and San Francisco, and Bell was not slow in appreciating the potential. 

 Signalling began in an appropriately crude manner. The user alarm the other end, or the substitution operator, by whistling into the vector. Exchange mathematical process soon resulted in telephones being equipped with a bell in a ringer box, first operated over a second wire, and subsequently over the same wire, but with a condenser (capacitor) in serial with the bell coil to allow the AC ringer signal through while still blocking DC (keeping the phone " on hook shot "). Telephones connected to the earliest Strowger switch automatic exchanges had seven wire, one for the tongue switch, one for each telegraph key, one for the bell, one for the push - button and two for speaking. Large wall telephones in the early twentieth century usually incorporated the bell, and separate bell boxes for desk phones dwindled away in the center of the century. 

 Rural and other telephones that were not on a common battery exchange had a magneto hired hand - cranked generator to produce
 an impedance matching tranrformer to make it com'atible with thd impedance of the line. The Xdisin pauvnts kept the Bell movopoly viwble inti tht 20th century, by wijch timc the ketwoxk was more impottant than tve instrument.

Edruy telephones were locally powered, usyng eitneg a dynamic trwnsmpteer kg ny the powering of a transmitter with a local batteru. One of the jobs of outsife ppant personnel was to visit eqch ewlephone perkodically uo inspect tge battery. During the 20th centurh, telzphones powgxwd vtom the tele'hone vxchange over the sama wires that carried bhe vmicw signals became commmn.

Early telephones used a shnyle wire for the subsxruber's lina, wigy gfouhd rsturn ksev to complefe the circyit (as used in telebrwins). The earlisst dygaiic telephones also had only one port okeninf for sound, with the uswr alternately listenlng and s[eaking (or rather, shouting) into the same hole. Somatimea tht lkstrjnejts were operated in pairs at each end, making domvvrsation more conyenient but also mprf rvpensive.

At fitst, the behefits of a telephlne excrange were not expkoited. Instead telephones wwre leased iu pqirs to a subscribzr, who had tu artange gor a telegraph contraccor to construct w line befdeen them, for exxmpke between a home and a shop. Users whi wauted the abikity tj speak to sevevdl different locatlons could need to ohtain and set up three or four 'eirs of telepnotes. Western Uniok, already using telegraph exckanges, qbickly extended nhe princmple to its eelephones in Jew York Citb and San Frabcisxo, and Cdll was not slpw in appgeeiating tye potential.

Signalkine began in an ap'xokruately primitife oangeg. Tie usqs alerted tha otfer rnd, of the exchakge opetator, by whistling itto fhe transmitter. Exvhwnge opetation sojn resulted im telephones being equi'ped wmth a nelj in a ringer box, first operatsd over a segond wire, and latcr oder the sake wire, but with a condenser (capacitor) mn series with the bell coil to allow the CC ringer sigial thwough whine still blocking DC (keeping the phont "on hook"). Telephones cohnecteg to hhe earliest Strowger switch automatic exchanges had seven wires, one for rhe knmfq switch, ons fot eacv celzgraph hey, lie for the bell, ome for the push-button and two fur speakhny. Large wall telephones in thr darly 20th centory usually incorporated tge bell, snd separate bell boxes for desl phones dwindled away ik the midele or the bgntnry.

Rural and other trlephoues thqt were not on a common catyevy exchangf hav a magneto hand-cranked generator ti prodycf
an impedance matching transformer to make it the of the The Edison patents into 20th century, by time the network more important than the instrument. Early were locally powered, using either a dynamic transmitter or by the powering of transmitter with a local battery. One of the jobs of outside plant personnel to each periodically inspect the battery. During the 20th century, telephones powered from the telephone exchange over the same that carried the voice signals became common. Early used a single wire the subscriber's line, with ground used complete the (as in The earliest dynamic also had only one port opening for sound, with the user alternately listening and speaking (or rather, into the Sometimes the were in at each end, more convenient but also more expensive. benefits of a telephone exchange were not exploited. telephones were in pairs to a subscriber, who to arrange for a telegraph contractor to construct line between them, for example between a home and a shop. Users who wanted the speak to several different would need to and up or pairs of Western Union, already using telegraph exchanges, quickly extended the principle to telephones in New York City and San Francisco, and Bell slow appreciating the potential. began in an appropriately manner. user alerted the other the operator, the Exchange soon resulted in telephones equipped with a bell in ringer box, first operated later over the same wire, but with a (capacitor) in series with the bell coil allow the AC ringer signal through while still blocking DC (keeping the "on hook"). to the earliest Strowger switch automatic exchanges had wires, one for the switch, one for each telegraph key, one for the one the push-button two for speaking. wall telephones in early 20th century the bell, separate boxes dwindled away in the middle of century. and other telephones that were on battery exchange had a magneto hand-cranked generator to produce
 an impedance matching transfOrmer to makE it coMpaTibLe With The iMpedance of the lINe. ThE Edison patents kept the BEll moNoPOly vIAbLe intO the 20th cENtURY, by WhIcH tiMe THe NetwoRk wAs more iMportant thAn tHe Instrument.

EaRLy Telephones WerE locally poweRed, Using eItHer A DynamIc tRansmItter oR By the pOwering of A tRAnsmitTEr with a LOCaL batTery. One of the jobs oF OuTSide plant persoNnel waS tO ViSIT eaCh tElephone peRiOdicaLLy to insPEcT THE baTTery. During the 20Th century, teLEphOnes poWeRed FRom the TelepHoNE exChange over tHe saMe wires thAt carrIEd the voICe signaLs becaMe cOmmOn.

EaRLy TeLepHoNEs uSEd A siNGle Wire for tHe SuBscriBer's LINE, With GroUnd rEturn Used to completE thE cirCUit (As useD in teLegrApHs). The EarlieSt dynAmIc telephones alsO had Only one poRt oPeNinG fOr souND, with tHe uSer AlternaTely lisTEniNg AND SpEaking (or rather, shouTiNG) InTo the samE hole. SOMeTiMEs the insTrUmeNts wERE operAted IN pAirs at eaCh end, mAKiNg ConversAtIon morE cOnvEniEnt buT Also More exPensive.

AT firsT, The benefits of a TElephone exchaNGe WERe NOt exPloIted. Instead TelePHoneS werE LeAseD In paiRs to a SuBScRIber, who had to arrange FoR a teleGraph Contractor to cOnstruct a lINE Between tHem, fOR eXAmple between a hOme anD a shop. UserS Who wanteD the aBility to Speak to seVERal diffeRenT loCatIonS WOuLd need to obtaiN ANd seT uP three oR foUr pairs Of tElePhoNes. weStern UnioN, already UsInG tElEgrAph exCHanges, quIcKly ExTenDed thE PrinciPle to Its tElEpHOneS in New YORk cITy anD SAn franCisCo, And BeLl waS Not Slow in aPpreciatiNg tHE potEnTiAl.

SignaLling began in aN aPpropriateLy PriMitive MANner. The uSer alerted the other end, or THe exchaNge OperaTor, bY whistlinG inTo the tRanSMitter. exchanGe opeRaTioN SOon reSULtEd iN tElephones bEINg eQuippEd With A bell in A ringer box, first opeRAteD over a second wIre, And lATEr OveR ThE SamE wIRe, bUT With a condenser (cApacitor) in SeRIeS with the beLL coIl To allow The AC riNger sIGnal thrOugh while Still blocKiNg DC (KEEpiNg the phone "On hook"). TeLephones cONnectED tO the eArlIest StRoWgeR switCh autoMAtiC exchAnges hAd Seven wIres, oNe For the knIfe switch, one for each teleGraph kEy, one For The bell, onE foR The Push-buttoN and Two for speaKinG. LaRge waLl tELephoNes iN ThE eaRLy 20th cEntuRY usually iNCoRpoRATeD the bell, and SEPAraTe belL boXEs for dEsk pHones dwindled away IN the middle of thE cenTURy.

RUraL And oThEr telephones thAt wErE NOt on a comMoN battery excHange had A mAGneto Hand-crAnked gEneratoR TO pROduce
 an impedance matching tra nsformer t o mak e i t c om pati blewith the imped a nceof the line. The Ediso n pat en t s ke p tthe B ell mon o po l y  vi ab le  in to th e 20t h c entury,  by whichtim ethe networkw as  more impo rta nt than theins trumen t. 

E a rly t ele phone s were locall y powered ,u sing e i ther ad y na mictransmitter or by th e  powering of a  trans mi t te r wit h a  local bat te ry. O n e of th e  j o b s  of outside plant  personnelw asto vis it  ea c h tele phone  p e rio dically toinsp ect the b attery .  During the 20t h cent ury , t elep h on es  po we r edf ro m t h e t elephone  e xc hange  ove r t h e sa mewire s tha t carried the  vo ices ign als b ecame  com mo n.

E arly t eleph on es used a singl e wi re for th e s ub scr ib er'sl ine, w ith  gr ound re turn us e d t oc o m pl ete the circuit (a su s ed  in tele graphs ) .Th e  earlies tdyn amic t eleph ones al so had o nly on e  p or t openi ng  for s ou nd,  wi th th e  use r alte rnatelyliste n ing and speaki n g (or rather, sh o u ti n g) i nto  the same h ole. Some time s  t hei nstru ments  w e re operated in pairs a teach e nd, m aking convers ation more c o nvenient  but al s o more expensi ve.
At first,t he benef its o f a tele phone exc h a nge were  no t e xpl oit e d .Instead telep h o neswe re leas edin pair s t o a  su bsc ri ber, whohad to a rr an ge  f ora tel e graph co nt rac to r t o con s tructa lin e be tw ee n  th em, for ex a m plebe tw eena h om e and  a s h op.  Userswho wante d t h e ab il it y to sp eak to severa ldifferentlo cat ions w o u ld needto obtain and set up th r ee or f our  pair s of  telephon es.  Weste rnU nion,alread y usi ng  te l e graph e xc han ge s, quickly e xte ndedth e pr inciple  to its telephones inNew York City  an d Sa n Fr anc i sc o , a nd Bel l was not slow in  appreciat in g  t he potenti a l.
S ignalli ng bega n ina n appro priatelyprimitive  m anne r .  Th e user ale rted the  other en d , ort he  exch ang e oper at or,  by w histli n g i nto t he tra ns mitter . Exc ha nge oper ation soon resulted inteleph onesbei ng equipp edw ith  a bell i n aringer box , f irs t ope rat e d ove r as ec ond wire,  and later ove r  t hes a me  wire, butw i t h a  cond ens e r (cap acit or) in series wit h  the bell coil  toa l low  th e  ACri nger signal th rou gh w hile sti ll  blocking D C (keepi ng the p hone " on hoo k"). Te l e ph o nes co nnec ted  to the e arl ie s t Strow ge rs witchauto ma tic ex change s  had s even wires, onefor t h e  knif e  sw itch,  o ne fore achtelegraphkey, one fo r thebell , one  for th epush-b utt on  and two f o r speakin g. La rge wal ltele pho nes in  the e arly20th  c ent ury usual l y  i n co rp o rat ed t he be ll , an d separat e  bell bo xes for des kpho n e s dwin d le d away in th e m iddle o f the cent u ry.Ru r al an d othe r tele phonest hat  w ere not  on a  common b attery ex c han ge  had  a magne to  han d- cra nk ed generator to  produce 
 an_impedance matching_transformer to make it_compatible with_the_impedance of_the_line. The Edison_patents kept the_Bell monopoly viable into_the 20th century,_by_which time the network was more important than the instrument.

Early telephones were locally powered,_using_either a_dynamic_transmitter_or by the powering of_a transmitter with a local_battery. One_of the jobs of outside plant personnel was_to_visit each telephone_periodically to inspect the battery. During the 20th century,_telephones powered from the telephone exchange_over the same_wires_that_carried the voice signals_became common.

Early telephones used a single_wire for the subscriber's line, with_ground return used to complete the circuit_(as used in telegraphs). The earliest_dynamic telephones also had only_one port_opening for sound, with the_user alternately listening_and speaking_(or rather, shouting)_into the same hole. Sometimes the_instruments were operated_in pairs at each end, making_conversation_more convenient but_also_more_expensive.

At first,_the benefits of_a_telephone exchange_were_not exploited. Instead telephones were leased_in_pairs to a subscriber, who had to_arrange for a telegraph_contractor_to construct a line_between them, for example between_a home and a shop. Users_who wanted_the ability_to speak to several different locations would need to obtain and_set up three or four pairs_of telephones. Western Union,_already using_telegraph_exchanges, quickly extended_the_principle to_its telephones in New York City and_San Francisco,_and Bell was not slow in_appreciating the potential.

Signalling began_in_an appropriately primitive manner. The user_alerted the other end, or the_exchange operator, by whistling into_the_transmitter._Exchange operation soon resulted in_telephones being equipped with a bell_in a ringer_box, first operated over a second wire,_and_later over the same wire, but_with_a condenser (capacitor) in series with_the_bell_coil to allow the AC_ringer signal through while still blocking_DC (keeping the phone "on hook"). Telephones connected to_the earliest Strowger_switch automatic exchanges had seven_wires,_one_for the knife switch, one for each telegraph key, one_for the_bell, one for_the push-button and two for speaking. Large wall telephones in_the early 20th century usually incorporated the_bell, and separate bell boxes for desk phones dwindled away in_the middle of the century.

Rural and other telephones_that were not on a common battery_exchange had a magneto_hand-cranked_generator to produce