Britsh Telecommunications Engineering Volume 17 Part 4

108 Pages·443.9 MB·English

by  The Institution of Britsh Telecommunications Engineers

BRITISH
TELECOMMUNICATIONS
.. ’ ENGINEERING
BRITISH
TELECOMMUNICATIONS
ENGINEERING
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‘ .
Contents I I
VOL17 PART4 JANUARY1999
Customer Telephony Integration
Voice-DataConvergenceandtheCorporateVoice-over-IPTrial 218
AndrewCatchpole
Telecommunications in the213t Century
va6‐‘l'heNextGenerationInternet 225
StuartPrevostandTonyBenn
APlatformforElectronicCommerceServiceTrials 232
JohnWittgreffe
C P' t Agent-BasedSolutions forE-Commerce 237
over '0ure MartinOwenandJorgeNunezSuarez
BTCorporatePictureLibrary; WitherVideo?‐VideotelephonyinPerspective 245
aBTphotograph AlwynLewis,GrahamCosierandCharlesNightingale
BoardofEditors
ChairmanBillMills,M.A.,C.ENG.,M.I.E.E.
ManagingEditorPaulNichols,e.sc. SecretaryLesBrand,M.ENG.,M.B.A..D.I.c. TreasurerDenisTaylor,F.C.M.A.
AssistantEditorRichardKemp,B.SC.,c.ENG.,M.I.E.E. FlogerBlake,C.ENG.,M.l.MECH.E. JasonChilton MartinEvans,e.sc.,PH.D.
DavidGreenop,5.50.,M.SC. PeterHowell,3.30.,C.ENG.,M.I.E.E.,M.C.I.B.S.E,M.l0.M. SteveJordan,B.SC.,M.sc.,C.ENG.,M.l.E.E.
MurrayTrantor,B.SC.,C.ENG.,F.I.E.E.,D.M.S.,M.I.MGT.KeithWard,C.ENG.,F.l.E.E.,M.I.MGT. DavidWhite,M.I.P.D.,M.B.I.M.,L.l.A.A.
BritishTelecommunicationsEngineeringJournal,PostPoint2005,TheAngelCentre,403StJohnStreet,LondonEC1V4PLISSN0262-401X
Contents continued
VOL17 I PABT4 I JANUARY1999
Optical Technologies
AReviewofOpticalWireless 251
Whatisitandwhatdoesit offer?
DavidJ.T.Heatley,DavidFt.Wisely,IanNeildandPeterCochrane
MobilityandRadio Communications
ProfessionalMobileRadio‐Service,MarketPositionandTechnology 262
PaulTattersall
Customer Service
DevelopingCustomerServiceSkills 269
TrishJones
StructuredProcessImprovement
StructuredGreenfieldPlanning 274
KenCobb,MarkRoseandIanLawrence
GenOSys‐AutomatedToolforPlanningCopperGreenfieldNetworks 281
DonAsumuandJohnMellis
HumanFactors
‘TheEyeoftheBeholder’‐DesigningforColour-BlindUsers 291
ChristineRigden
EvolutionoftheBTUKCoreTransportNetwork 296
lanHawker
Video-BasedVirtualClubs 301
UsingMultimediato Re-presentTechnologytoWomen
GraemeBalfour,SylviaWilbur,HilaryJohnsonandStephenFurner
ConvergenceBetween PublicSwitchingandtheInternet 308
Hans-UlrichSchoenandStephanScholz
RegularFeatures
pcochrane@btlabs 314
BookReviews 315
TelecomFocus 316
ForthcomingConferences 320
Information Insideback
ThemeEditors
ComputerTelephonyIntegrationDougChesterman Telecommunicationsinthe21stCentury SteveSim
OpticalTechnologiesDavidSmith MobilityandRadioCommunicationsNigelWall CustomerServiceMarkJakeman
StructuredProcessImprovement KeithBeales
COMPUTERTELEPHONYINTEGRATION
Andrew Catchpole
Voice-Data Convergence.
and the Corporate
Voice-over-IP Trial
Theconvergenceof voice Introduction Whatis Voice over IP?
F r z ‘ fi r gEli W 5 1 . , “ A 1 ,7
anddata networksand
Thisarticleispartofathemediscuss‑ Unlikethetraditionalpublic
ingcomputertelephonyintegration switchedtelephonenetwork(PSTN),
technology hasbrought
(CTI).Thefirstarticle1definedCTIas whichisacircuitswitchednetwork,
new opportunitiesand thelogicalassociationbetweenthe VoIPusesapacketswitcheddata
voiceanddataworlds.However,since networkfortransportingvoiceand
threats totraditional thatfirstarticletechnologyhasmoved signallinginformation.
rapidlyforwardtowardsthephysical Figure1showsanIPtelephony
suppliers oftelephone convergenceofthevoiceanddata devicesuchasapersonalcomputer
communications. (PC)withfullsoundcapabilitiesand
switchingsystems.BT Thefirstpartofthisarticle connectedtoadatanetwork.Also
discussesoneaspectofthisconver‑ requiredissuitableInternettelephony
hasrecentlycompleteda
gencetechnology‐voice-over‑ clientsoftwaresuchasthefreely
Internetprotocol(VoIP)with availableMicrosoftNetMeeting
corporate voice-over-IP
particularattentiontointelligentIP application,althoughmanyothers
trial, involvingover switchingsystems,orsoft-PBXs. areavailable.
Thesecondpartgoesontodiscuss Voicecommunicationsisinitiated
50 users,andusinga new thetechnicalevaluationofasoft‑ toanotherVoIPclientbymakinga
PBXsystemin thecorporatevoice‑ calltotheIP addressofthedistant
breedofsoft-PBX over‐IPtrialrunbyBTfromJuneto client(ifknown)orbyusingoneof
October1998andinvolvingover themanyInternetlocationservers
switchingsystems. 50triallistsmakingover10000calls. (ILS)orgatekeepers,asshownin
Finally,someofthevalue-add Figure2.
applicationsaredescribedwhichare Oncethecallisconnected,basic
nowbeingrealisedasaresultof speechtransmissioncanthentake
voice-data convergence. place.VoIPworksbysamplingspeech
Figure1‐Voice-over‐IPtelephonydevice
218 British’IblecommunicationsEngineering,Vol.17,Jan.1999
COMPUTERTELEPHONYINTEGRATION
Figure2‐Simplegatekeeperrouted GATEKEEPER
VoIPcall
N
(normallyevery30ms)froma
microphoneintodatapackets,which
aretransmittedtoadistantreceiver
Viathedatanetwork.Insomecases,
thesespeechsamplesarecompressed
toreducebandwidthrequirements vomePACKETS
usingoneofmanycodingstandards.
WhentheIPpacketsarereceived 0 callprocessor, providedbythesoftwareofatradi‑
atthedistantend,theyarebuffered tionalPBX.Thecallprocessing
in memorybeforebeingdecodedand 0 gateway, softwareresidesonaservercompu‑
playedoutthroughthesoundsystem. tersystemconnectedtotheIP
Generally,datanetworkapplica‑ 0 userterminal,and networkandgivesbasiccallhandling
tionsusehigher-levelprotocolsin the (forexample,routingofinternaland
IPfamily.MostIP telephonyapplica‑ 0 applications. externalcalls)aswellassupplemen‑
tionsusetheuserdatagramprotocol taryfeaturessuchascalltransfer
(UDP),whichismostsuitedtoreal‑ UnlikeaconventionalPBX,no andcalldivert.It doesnotnormally
timedatasuchasvoicebutgivesno switchingelementisrequiredto processtheactualspeechinformation
guaranteethatthepacketswillever connectthevoicepaths.Voicetraffic itself,althoughexceptionstothis
arriveatthedestination.Signalling iseffectivelyswitchedwithinthe includeapplicationssuchasvoice
andcallcontrolinformationis existingdatanetworkasIPpackets. mail.
generallycarriedusingtransmission Aunifiedcommunicationsinfra‑
controlprotocol(TCP)which,unlike structuretothedesktopallows User Terminals
UDP,doesprovideguaranteed commondeliveryofvoiceanddata
deliveryofpacketsoveranIP withthepotentialofreducedinstal‑ Asoft‐PBXuserterminalisgenerally
network. lationandmaintenancecosts.It also basedonanindustry-standard
Foracomputerliterateperson, potentiallylowersthecostoftelecom‑ multimediaPCandspecialIP
simpleVoIPisrelativelyuncompli‑ municationswhenconnectingremote telephonyapplicationsoftware.Over
catedtoset-upandusebutstilllacks offices.Sincevoiceanddatashare thelastyear,however,newtypesof
theubiquitousnatureofthetelephone thesamedatanetwork,voicecan IPtelephonehavestartedtobecome
network.Asoft-PBXbridgesthegap easilybeextendedtoacompany’s commerciallyavailable‐theIP‑
betweensimpleVoIPandacommer‑ WAN.In practicetheWANwould,in phoneandthePC-basedsoft‐phone,
cially-viablefully-functionalvoice mostcases,havetobeupgradedto describedbelow.
network. supporttheadditionalreal-time
bandwidthrequirements. Pc-basedsoft-phones
Soft-PBX Developments Otherpotentialsavingscanbe Soft-phonesarePC-basedInternet
realisedbyusingspeech-compression telephonyapplicationswhichexploit
Asoft-PBXdiffersfromatraditional andsilence-suppressiontechniques, thePC’smultimediacapabilitiessuch
PBXowingtotwoimportantcharac‑ whicharenormallycost-justifiable assoundcard,loudspeakersand
teristics.Firstly,callprocessingis onlyininternationalnetworks.Audio microphone.Soft-phonescanprovide
performedbyasoftwareapplication compressionmeanslessbandwidthis allthebenefitsofCTIapplications,
executedonanindustrystandard requiredtotransmitvoicesoband‑ themajordifferencebeingthatthe
computingplatform.Secondly,the widthisusedmoreefficiently. soft-phoneapplicationalsohandles
voiceandsignallingarecarriedover AllthetraditionalPBXfeatures theaudiostreams(voice)aswellas
adatanetworkratherthana areprovidedbythesoft-PBXbut callcontrol.
separatetelephonenetwork‐usually withtheadditionofmultimedia Soft-phonesallowtelephonyusers
anIPnetwork. applicationssuchasdataandvideo tolog-onandacquireaccesstoa
This,in theory,allowsthereplace‑ collaboration,whichbecomemuch company’stelephonesystemfrom
mentofconventionalbusiness easiertoincorporatein asoft-PBX anyremotesitehavingan IP connec‑
telephoneequipmentandwiringby environmentandatalowercostthan tionbacktothecall-processing
integratingdataandvoicetraffic ISDN‐basedsolutions. server.
overasinglelocalareanetwork Soft-phonesshouldbeableto
(LAN)orwideareanetwork(WAN) CallProcessor supportallthefeaturesthata
infrastructure. conventionalPBXtelephonesup‑
Asoft-PBXsystemconsistsofthe Thecallprocessingfunctionofasoft‑ portsand,in addition,canhaveeven
followingfunctionalcomponentsin PBXprovidesallthenecessarycall moreuser/systemprogrammable
additiontothedatanetworkitself: controlandsignallingnormally features.
BritishTelecommunicationsEngineering,Vol.17,Jan.1999 219
COMPUTERTELEPHONYINTEGRATION
Figure3‐Corporatevoice-over‐IP SOFI-PBX BYLABORATORIES,
BTCENTRE.WNW" MARTLESNAMHEAT"
trialarchitecture CALLMANAGER
lP-PHONE
~~~~~
- _ ‑
OnelimitationofaPC-basedclient
thatcouldafi'ectuseracceptancewould
bethelowervoicequality,specifically ,l
.2 IP
thehigheraudiodelayswithinthePC. « E / VIRTUAL
TELEPHONE
However,specialtelephonysound
cards,suchastheQuicknetPhoneJack,
areavailablewhichprovideenhanced
Mum-PROTOCOL
audiocapabilitieswithon-board ROUTER
NETWORK
hardware-basedspeechprocessing,full
~-------‑
duplexspeechandechocancellation.
Importantly,thecardprovidesaddi‑
tionalconnectionsforaregular
analoguetelephonehandsetand
headsetifrequired.
BTNEI'(INTERNALVOICENETWORK)
IP-phones
IP-phonesarearelativelynovel
conceptappearingduring1998.The providethesetypesofIPgateways, managementfromanylocation
maindifferencefromaregular describedlater,toperformtoll-bypass withintheBTintranet.
telephoneisthatanIP-phoneis applications.Inthefuture,PBXswill Thecallmanagerdialplan
pluggedintoanofficeLAN,whereas haveIPtelephonylineinterfacesas allowedflexibleroutingstobe
normalPBXtelephonesrequirea wellasconventionallinecards. configuredforinternalandexternal
separatetelephonecablingsystem IPtelephonygatewayscanbe numbers.Forexample:London
(althoughit isnowcommonpractice usedin asoft-PBXsystemtomake triallistswereallocatedfour-figure
touseastmcturedcablingsystemfor andreceivecallstothePSTNor numbers,whileothertriallistswere
bothdataandtelephony). otherconventionalPBXsystems. allocatedsix-figurenumbers.All
Also,unlikeastandardtelephone, usersweregiventhesameinternal
anIP-basedtelephonecanbe CorporateVoice-over-IP numberastheirregulartelephone
installedanywherein acorporate Trial number.Thetriallistswereableto
LAN/WANnetwork,whileretaining divertallincomingcallsfromtheir
itsuniqueidentity,withoutrequiring Anumberofpotentialsoft-PBX normalPBXtelephoneontothesoft‑
adedicatedconnectiontothePBX. solutionswereshortlistedforBT’s PBXusingaprivate(ex-directory)
SettingupanIP-phoneismoreakin corporateVoIPtrial.Requirements number.AccesstothePSTNand
tosettingupaPC’snetworkconfigu‑ forthetrialsystemwerethatit BTNetwasavailablebydialling9
rationrequiringhostandserverIP wouldhaveISDN(primaryrate) and00respectively.
addressdetails. gateways,ITU-TH.323standards‑ Calldetailrecordsprovideda
basedPCclientsandideallyIP historyofallcallsmadeonthis
IPTelephony Gate ays telephonesaswellasofferingas systemandthiscouldbelinkedto
manyPBXfacilitiesaspossiblesuch anybillingsystemif required.
AnIPtelephonygatewayallowsIP ascallrecords. Duringthetrial, inexcessof10000
telephonecallstobeconnectedwith Thefollowingparagraphsdescribe callsweremadeusingthesystem.
thetraditionalPSTNorPBXnet‑ themaincomponentsoftheBT
works.Gatewaysarealsoknownas corporateVoIPtrialsystem.Figure3 IP telephony gateway
PSTN-to-IPgatewaysorsimplyPIGS! describesthearchitectureofthesoft‑ AnumberofIPtelephonygateways
Gatewayscanbeeitherdigital, PBXsystemusedin thetrial. wereconnectedtotheMeridianPBXs
connectingtotheISDNnetwork atBTCentrein LondonandBT
(basic-orprimary-rateISDN),or Soft-PBXcall manager Laboratorieswhichallowedcallsto
analogue,connectingtoregular Thesoft-PBXcallmanager,which andfromthePSTNortheBT
PSTNlines. runsonanNTserverplatform, internaltelephonenetwork.
Gatewayscanalsobeusedto providedallthecallprocessingand Thefirstgatewaysdeployed
interconnecttwoormorePBXsviaan remotemanagementfunctions supported onlyITU-TG.711
[Pnetwork.Inthisconfigurationthe requiredforthetrial. uncompressedvoiceusing64kbit/s.
useofvoice-over-IPisasimple Thesoft-PBXserverwasadminis‑ However,it isnowpossibletouse
replacementtransportsystemwhich teredthroughaWorldWideWeb voicecompressionat 6-3kbit/susing
doesnotrequireaseparatecall (WWW)browserinterfacewhich theITU-TG.723.1recommendation.
processingfunction.Manyvendorsnow allowedremoteconfigurationand (Note:Voiceis compressedonlyon
220 BritishTelecommunicationsEngineering,Vol.17,Jan.1999
COMPUTERTELEPHONYINTEGRATION
theIPtelephonyside;thePSTNis PCtobeconnectedtotheIP-phone. thatisfreelyavailableandusesthe
always64kbit/s.) ThisallowedasingleLANporttobe ITU-TH.323recommendationfor
Analoguegatewaysarealso usedforboththeIP-phoneandthe multimediacommunications.By
availablebutthesewerenotused PC,althoughanIPaddressisstill addingtheseuserstothesoft-PBX
duringthetrial.Thesegatewaysare requiredforeachdevice. systemtheywereabletoutilisetheir
usefulforconnectingtoregular IPaddresseswereallocated H.323clienttoinitiateandreceive
analoguetelephonelinesortoconnect staticallyorbyusingdynamichost callstoothertriallistsusingtheIP‑
analoguedevicessuchasanswering configurationprotocol(DHCP)which phones.In addition,H.323users
machines,faxmachinesandmodems. isastandardinthedatanetwork wereabletousetheIPtelephony
ThegatewaysusedwereallITU environmentforconfigurationand gatewaystomakecallstothePSTN
H.323compliantwhichallowedfull managementofnetworkedcomput‑ andtoreceiveincomingPSTNcalls
interoperabilitywithothervendors’ ers.Thispotentiallyreducesin‑ usingadirectdial-in(DDI)number.
H.323gatewaysandH.323PCclient servicecostsbyallowingIP-phones
applications. tobemovedandreconnectedany‑
Managementofallthegateways whereontheIPnetworkwithno
wascontrolledthroughthesame configurationchangesrequired.
WWWmanagementinterfaceasthe employedtolinktraditionaltelephony
callmanager. Soft-phones networksacrossanIPnetwork,thus
ThePC-basedsoft-phoneis alow‑ allowingnetworkconsolidationand
IP-phones costalternativetotheIP-phone.The potentialreductionsinPSTN
TheIP-phoneisequivalenttoaPBX soft-phonesoftwarewasinstalledon charges.Thistypeofservice,com‑
featuretelephonesuchastheMerid‑ adesktop(orlaptop)PCequipped monlyknownastoll-bypass,canbe
iantelephonescommonlyusedin ET withasoundcardandmicrophone.It usedtoroutevoicecallsorevenfax
Themaindifferencewasthatthey combinedthefeaturesetoftheIP‑ callstransparentlyacrosstheIP
wereconnectedtotheofficeLAN phonewithanumberofadditional network.
ratherthanadedicatedtelephone multimediafeaturessuchasdata Figure4showsasimilartoll‑
wiringnetwork.Thetrialdeployedup andvideoconferencing. bypasssystemwhichwasused
to50IP-phoneswhichgaveusers Thesoft-phonecurrentlysupports duringthetrialfornormalPBX
desktopconnectivitytothesoft-PBX. onlyITU-TG.711uncompressed telephoneusersbutunderthecontrol
EachIP-phonerequireda10baseT speech.Thismeansthatit isnotyet ofthesoft-PBXcallmanager:Specifi‑
LANconnectionanda48VDC suitableforremoteworkingover callyBTLaboratories’telephone
powersupplyunit.A11telephones dial-upconnections.However,it is userswereabletodialaunique
hadprogrammablefeaturebuttons, hopedtohavethiscapabilityavail‑ accesscodeontheMartlesham
hands-freefacilityandLCDdisplay ablelatertogivereal‘roadwarrior’ MeridianPBXtoroutecallsto
thatallowedthecaller’snumberand abilityforthecorporateuser. LondonandthenontoanyUK
nametobedisplayed.EachIP-phone telephonenumberusingthesame
wasconfigurabletouseeither H.323telephony clients corporatedatanetwork(multi‑
compressedoruncompressedspeech. Someusersoptedtousetheir protocolrouternetwork(MPRN)).
SomeofthetelephoneshadLAN existingInternettelephonyapplica‑ Over400peopleatBTLaborato‑
repeatersthatallowedthedesktop tionssuchasMicrosoftNetMeeting rieswereinvitedtoparticipateinthe
Figure4‐Simpletoll-bypasscallfromaPBXtelephonetoanotherPBXtelephone
BritishTblecommunicationsEngineering,Vol.17,Jan.1999 221
COMPUTERTELEPHONYINTEGRATION
toll-bypassservice.Interestingly differentIPnetworkconditionsand foraVoIPtriallistandautomatically
noneoftheadditional400triallists differentspeechcoderstogetherwith establishacalljustbyclickingonthe
wereawarethatit wasaVoIPtrial, PBX,internationaldirectdial(IDD) hyperlinktelephonenumber.The
justanewtelephoneservice! andGSMdigitalmobilecalls. directorycontentwasthesamedata
Alternativelythetoll-bypassservice Tocomplementthesesubjective ascontainedwithinthesystem
wasalsoavailableremotelybydialling testmethods,anewETLaboratories configurationsowasalwaysup-to‑
aspecialaccessnumber.Thecallwas testtoolcalledperceptualanalysis dateandcorrect.
automaticallyansweredusinga measurementsystem2(PAMS)was
MeridianIVRsystemwhichprompted alsousedwhichwasabletopredict Dataconferencing
theuserforasecuritynumber.If speechqualityovertheVoIPend-to‑ Withasoft-PBX,thecommunications
correctthentheuserwaspromptedfor endconnection.Thetestswere mediumisnolongerrestrictedto
therequireddestinationnumber.Once performedbyinjectingspeech-like voiceonly.BoththeIP-phoneand
enteredthecallwasthenpassedtothe signalsatoneendandcapturingthe soft-phoneareabletoadddata
soft-PBXforonwardrouting. degradedsignalattheotherend.A conferencingtoanyIP-to-IPcall,on
ByusingeithermethodthePSTN qualitypredictionwasthencom‑ demand,atanytimeduringavoice
betweenBTLaboratoriesandBT putedfromamathematicalcompari‑ calljustbypressinganappropriate
Centrein Londoncouldbebypassed sonbetweentheoriginalsignaland featurebutton.Thisisachievedby
byusingtheVoIPnetwork. thedegradedsignal.ThesameITU theIP-phoneworkinginparallel
listeningscale,aswithsubjective withthePC-basedsoft-phoneclient.
Voice Quality using IP testing,wasthenpredicted.The Dataconferencingtoolsinclude:
Telephony resultsfromtheobjectivetesting,
1 usingPAMS,wasthencompared 0 applicationsharing,
Threedifferentmethodswereused withtheperformanceofthecorpo‑
duringthetrialtodeterminethe ratedatanetworkatanygiventime 0 white-boarding,
voicequalityofIPtelephonyin a ofdaytocheckforanycorrelation
corporateenvironment: betweenthedatanetworkconditions 0 filetransfer,
andthepredictedqualityofservice.
0 useropinionscores, Knowledgegainedfi‘omthetrial,in 0 textchat,and
particularthetestingdiscussedabove,
0 subjectivetestingin acontrolled hasprovidedessentialinformation O videoconferencing
environment,and requiredtospecifyacommercially
acceptableVoIPtelephonysolution. Thesecollaborativeworkingtools
O objectivetestingusingnewET areusefulforreviewingdocuments
testtools. Applications orshowingslidepresentations
remotely.Byaddingarelatively
Thefirstmethodrequiredusersto Thesoft-PBXprovidesseveral cheapvideocameratoadesktopPC,
registertheiropinionofthevoice interestingapplicationswhichwere videoconferencingbecomesan
qualityaftereachIPtelephonecall. investigatedduringthetrial. inexpensiveandsimple-to-usereality.
Thisprocesswasautomatedbyusing Thesoft-PBXnowbecomesamulti‑
speciallyprogrammedkeysonthe Voice mail media-PBX.
telephonetoindicatecallquality Thevoice-mailserviceallowedusers
usingtheITUlisteningscaleof torecordtheirownpersonalised GTISupport
Excellent,Good,Fair,PoorandBad. greetings,aswithatelephoneanswer‑ l
Arunningtotalwasusedtodeter‑ ingmachine,onthesoft-PBXvoice
minetheoverallopinionscoresofthe mailserver.Anyunansweredcalls IP-basedterminaldevice:IP-phones,
triallists.Althoughausefulindicator, werethenforwardedtothevoicemail soft-phonesandH.323terminals.
thismethodwaslessthanidealas serverwhichplayedthegreetingand Applications(softwareorhard‑
theresultswerenotobtainedin a recordedthecaller’svoicemessage. ware)couldbedevelopedtomakeuse
controlledandrepeatablefashion. Therecordedvoicemessagewasthen oftheH.323interface.However,
ThesubjectivetestfacilityatBT senttotheuser’se-mailaccountasa thesewouldbelimitedtothebasic
Laboratorieswasusedtocarryout soundfile,effectivelyprovidingthe H.323functionality;forexample,call
moreformalsubjectivetestingthat userwithaunifiedinboxsystem. set-upandcleardown.
wascontrolledandrepeatable.This TheIP-phonesandsoft-phones
involvedasetoftestsusingrealpeople Clickto calldirectory useaproprietarysignallingprotocol
makingVoIPcallsoveranumberof AsimpleWWW-baseddirectorywas usedbetweenthesoft-PBXserver
configurableconditions;forexample, setupthatallowedanyonetosearch andgatewaysandterminals(tele‑
222 BritishTelecommunicationsEngineering,Vol.17,Jan.1999
COMPUTERTELEPHONYINTEGRATION
phones)andprovidemuchgreater Exampleapplicationsincludethe asoft-ACDarchitecturedoesnotuse
functionality.Usingthisprotocol,or abilityforpeoplebrowsingtheW atraditionalcircuitswitchedPBXor
H.323,it wouldbepossibletodevelop toinitiateamultimediacalltoacall ACDsystem.InsteadtheVoIPis
CTIapplicationswithdifferent centreassociatedwithacompany’s usedtoprovideend-to-endconnectiv‑
graphicaluserinterfaces(GUIs);for WWWpagebyclickingonaCALLME itybetweenthecustomerandthecall
example,aBT-look-and-feelapplica‑ button.Thecustomerandthecall centreadvisorthatallowsfull
tion.Analternativeapproachwould centreadvisorcanthentalkandsee multimedia(voice,videoanddata)
betousetheMicrosoftTelephony eachotheraswellasexchange communications.
ApplicationsProgrammingInterface informationanddata;forexample,to
(TAPI). completeamortgageapplication IP-Centrex
form.Oneexampleisthe‘CallMe’ Centrexis anetwork-basedvirtual
Telephony API (TAPI) serviceontheBTShopWWWsite privatenetwork(VPN)suppliedby
TAPIwasdevelopedbyMicrosoftand (http://wwwbtshop.bt.com/). telcosfordeliveringvoiceservicesto
Intelandhasbeenavailablefor IP-basedmultimediacallcentres largecorporations,oftenover
severalyears. areseenasoneofthemoresignifi‑ distributedsites.Centrexcouldbe
TheTAPIsoftwarearchitecture cantvalue-addapplicationsfora lookedonasbeingaPBX-in-the‑
allows,in theory,anyTAPIapplica‑ soft-PBXsystem. network’service.
tiontoworkwithanyTAPIserver However,therearethreeevolu‑ IP-Centrexisthesameideabutin
provider;forexample,aTAPI tionaryphasesoftheInternetcall thiscaseutilisesacompany’sIP data
compatibletelephone. centredevelopment: networkto deliverthevoiceservices
Recently,TAPI2.0wasreleased tothedesktop.In thefuture,it may
whichattemptstoaddressfunction‑ 0 Internetcallmeback, nolongerbenecessarytohavea
alityrequiredin acorporatePBX separatePBXoneverycustomer’s
environmentandcomesaspartof 0 VoIPbreakouttoexistingcall site.Allcallprocessingcouldbe
WindowsNT4.0platform.TAPI2.0 centre,and achievedbythesoft-PBX(IP‑
isthelatestiterationthatisbuiltin Centrex)serverwithintheprovider’s
totheclientandserveroperating O soft-ACD(automaticcalldistribu‑ network.TheVoIPtrialwaseffec‑
systemsandprovidessupportfor tor). tivelyIP-Centrexwithallcalls
third-partyCTIapplicationsl.These controlledbyacentralcallprocessor.
applicationscanthenworkacrossa TheInternet‘CallMe’functionhas WithIP‐Centrex,accesstothe
numberoftelephonysystems beendemonstratedbymanycompa‑ PSTNcanbeprovidedlocallyon
includingPBXs. niesbutsofarallthesesolutions customers’sitesorcentrallyin the
requireasecondlinetobeavailableor networkbytheserviceprovider.This
Potential Opportunities foraPSTNdialbacktobeinitiated allowssharingofthePSTNgateway
oncetheInternetconnectionhas resourcesandbreakoutoftheIP
HavingasuitableCTIinterface cleared.Theformerobviouslyisnot networkat themosteconomicpoint
wouldallowthebasicsoft-PBX financiallyacceptableinmostresiden‑ in acountryortheworld.This
concepttobeenhanced.Examplesof tialsituationsandthelattermeans potentiallyallowsIPcallstobypass
these‘valueadd’applicationsare thatdatasharingisnolongerpossible. normalnationaloreveninterna‑
givenbelow: VoIPbreakouttoanexistingcall tionaltelephoneroutes.Ultimately
centrecanbeusedtorouteInternet thiscouldleadtotheformingof
Internetcallcentres initiatedvoicecallsviaagatewayto manysmallbutflexiblesoft-telcos.
Overthelastfewyears,callcentres aconventionalcircuit-switchedPBX/
havebecomeakeytechnologyarea ACD. Web video screen telephones
formanycompaniesandorganisa‑ Anumberofcompaniesaredesigning
tionsbothlargeandsmall,localand Soft-ACD anddevelopingadvancedscreen
global.However,thetechnologyto Asoft-ACDallowsacustomer telephonetechnologieswhichalready
datehasbeenfocusedtowards browsingtheW toinitiatea supportIP telephony.
handlingpurelytelephone-based multimediacalltoacallcentre Targetmarketsforscreentele‑
customers.Atrendisemergingfor associatedwithacompany’sWWW phonesinclude:
thesecentrestobecustomercontact pagebyclickingonaCALL’buttonas
centreswherethecommunications withtheexampleabove.However, 0 corporatemultimediadesktop,
channelwillextendfromaudioonly withasoft-ACDthecustomerand
toincludee-mail,WWW,videoand thecallcentreadvisorcan,intheory, 0 screentelephoneforsmalland
datacommunications,effectivelya talkoverthedatanetworkusing mediumenterprisestodeliver
multimediacallcentre. VoIP.Thisis achievableonlybecause advancednetworkservices,and
BritishTelecommunicationsEngineering,Vol.17,Jan.1999 223
COMPUTERTELEPHONYINTEGRATION
0 mass-marketIPtelephonyappli‑ References Biography
ance(thatis,non‐PCdependent). . '7.’ i i7 7 7 7 *’ 7 '’ 7 " "'1" Z" ’7'}
1 CATCHPOLE,A.,CROOK,G.,and AndrewCatchpole
ScreentelephonescouldallowBT CHESTERMAN,D. Introductionto BTNetworksand
toprovidefullmultimedia(voice, ComputerTelephonyIntegration. InformationServices
videoanddata)desktopcommunica‑ Br.Telecommun.Eng,July1995,
tionsandcouldprovidehigh-func‑ 14,p.98.
tionalityeasy-to-usedesktopaccess
toallthebusinessapplicationssuch 2 Forfurtherinformationon
ase-mail,corporatedirectoriesand PerceptualAnalysisMeasurment
\
mobilityapplications.AdvancedBT System,contactRichardReynolds,
applicationscouldalsobe BTLaboratories, AndrewCatchpolejoinedBTasan
downloadedontothetelephone [email protected] apprenticein 1981in theNorwich
withouttheneedforexpensive TelephoneArea.In 1989,hetrans‑
firmwareupgradesorsoftware Glossary ferredtoBTLaboratoriesandisnow
upgradestodesktopPCs. aseniorprofessionalengineerin the
Anotherpotentialmarketisthe ACD Automaticcalldistributor NetworkIntelligenceEngineering
hotelbusinesswherescreentele‑ API Applicationprogramming Centre.Hismainworkhasinvolved
phonescouldeventuallybeprovided interface investigatingcomputertelephony
in everyroomofahotel.In theory,a GTI Computertelephonyintegra‑ technologyandapplicationsforthe
hotelguestcouldswipeacorporate tion desktop,officeandcallcentre
smartcardanddownloadcorporate DHCP Dynamichostconfiguration environments.Hehasalsoworkedon
computer/telephonyservicestoa protocol anumberofideasforadvanced
hotelscreentelephone.Thereal DN Directorynumber multimediacallcentresresultingin a
opportunityhereisnotjustthe 6.711 ITU-Trecommendationfor patent.Inhismostrecentworkhe
terminalbutthesoft-PBX(orsoft‑ codingofanaloguesignalsbypulse hasbeeninvestigatingopportunities
telconetwork)tosupportthesenew codemodulationat64kbit/s withIPtelephonywhichculminated
IP-basedmultimediaterminalsand 6.723 ITU-Trecommendationfor in therecentBTcorporateVoIPtrial.
thenetworkcentricapplications multimediacommunicationstrans‑ Hewasoneofthefirststudentstobe
whichwillbedownloadedontothem. mittingat5-3and6-3kbit/s awardedtheMartleshamM.Sc.
H.323 ITU-Trecommendationfor degreefromtheUniversityof
The Future packet-basedmultimediacommuni‑ London.
cationssystems
BThasgainedmuchknowledgeand IP Internetprotocol AndrewCatchpolecanbecontacted
understandingfromtheVoIPtrial. ISDN Integratedservicesdigital at [email protected].
WorkatBTLaboratorieswill network
continuetoinvestigatethetechnical ITU-T InternationalTelecommuni‑
opportunitiesfortheconvergenceof cationUnion(Telecomunnications
voiceanddatanetworksandsoft‑ StandardizationSector)
PBXswitchingarchitectures. IVR Interactivevoiceresponse
Furtherworkwillalsolookinto LAN Localareanetwork
theopportunitiesofconvergence PBX Privatebranchexchange
applications.In thefuture,as PC Personalcomputer
bandwidthbecomesplentiful,it may Soft-PBX ServerbasedPBXusing
bethatapplicationsgeneratethe voice-over‐Internetprotocol
substantiverevenueratherthanjust T.120 ITURecommendationfor
callminutes. dataprotocolsformultimedia
conferencing
WAN Wideareanetwork
VoIP Voice-over-Internetprotocol
224 BritishTelecommunicationsEngineering,Vol.17,Jan.1999