40 IT Pro January/February 2010 P u b l i s h e d b y t h e I E E E C o m p u t e r S o c i e t y 1520-9202/10/$26.00 © 2010 IEEE

MOBILE COMMUNICATIONS

Clinton M. BannerAlcatel-Lucent

The proliferation of messaging systems presents users with a challenging task: how to effectively use and manage many separate messaging systems. Unified messaging provides simplified management of different messaging systems through a single, unified interface.

D oyouwanttosendanSMS(shortmes-sageservice)messagetoafriend?You’llmost likelyuseanSMSclientonyourmobile phone to send it. Would you

liketouseinstantmessaging(IM)tofindoutifacoworker is available for an impromptumeeting?Chancesareyou’lluseaspecificIMclientonyourlaptopordesktopcomputertostartanIMsession.Do you find yourself trying to remember whichmessagingsystemapersonyouneedtocommuni-catewithuses—whether theyprefer textmessag-ing,email,oroneofthemanyavailableIMsystems?

The proliferation of different messaging sys-tems gives us more choices than ever to createand sharemessages. It also creates anewprob-lem:Howdoweaccessandmanageeachof themessaging systems we use throughout the day?Manyofushavebecomesousedtoworkingwithmultiplestratifiedmessagingsystems(seeFigure1)thatwedon’tconsideritatallunusualtostartourworkdayby

• checking for voicemail using a telephone ordedicatedinterface,

• loggingintooneormoreemailsystemstocheckformessages,

• startinguponeormoreIMsystemsindifferentdesktopwindows,and

•checkingfornewSMSormultimediamessageservice(MMS)messagesonamobiledevice.

Wehardlyevennoticeaswehopbetweenmessag-ing interfaces and devices throughout the workday, choosing the appropriate system to meeteachmessagingneed.Havewebecomesousedtoworkingwithmultiplemessaging interfaces thatwedon’texpectanythingeasiertouse?

Unified messaging (UM) seeks to solve thisproblembyprovidinganinterfacethatunifiesallofthesemessagingsystems.WithUM,youneedonly remember who you wish to communicatewith; UM will help you choose the appropriatemessagingsystem.TheUMinterfacewillprovideyouwiththesetofvalidcommunicationsoptions(forexample,textmessaging,email,orIM)basedon the current service capabilities of a selectedcontact. Insomecases, theuserwill specify thepreferredcommunicationmethod.Inothercases,

Understanding Unifi ed Messaging

computer.org/ITPro 41

theUMsystem itselfwill determinethebestwaytodeliverthemessagetoitsultimatedestination.

The Multiple Messaging Systems Problem TheUMvisioniscomplicatedbythefact that many existing messagingsystems have unique characteristicsthat reflect thecommunicationsdo-mains for which these systems weredeveloped.

Voicemail was developed for fixedandmobiletelephonysystems.It’susu-allyinvokedwhenauserisunavailableforavoicesession.Ausermustoftendialaspecialaccessnumbertoaccessandretrievevoicemailmessages.Moresophisticated systems support visualvoicemail interfaces and speech-to-textconversion.

SMS/MMS was developed for mo-biletelephonysystems.Shorttextmes-sages are sent asynchronously to thedestinationuserviaatelephonenum-berorshortcode.MMSletsusersaddrichcontent(suchasURLs,graphics,photos,orvideos)totheirmessages.

Emailwasfirstdevelopedforfixedandlaterformobilecomputertermi-nals. Email systems send messages asynchro-nouslytoanemailaddress(usuallyintheformofuser@domain_name.com)andletusersattachorembedrichcontent.

IMwasdeveloped first for fixedand later formobilecomputer terminals. IMsystemsuse (oremulate) a session-based model to support tex-tingandthesharingofrichcontentbetweenus-ers. Many IM systems also incorporate presencecapabilities,whichprovideinformationaboutre-moteusers’availabilityandwillingnesstocom-municatepriortoauserinitiatinganIMsession.

Often, these messaging systems are availableprimarily on the type of device for which theywere originally developed—for example, SMSandMMSarethemostprevalentmessagingsys-temsonmobiledevices,andemailandIMsys-temsareubiquitousoncomputerdesktopsandlaptops (although mobile device platforms haverecently begun supporting them). The increas-ing popularity of mobile devices that support

emailandIMfunctionality(Blackberries,smartphones, and so on) shows there’s a market formessagingsystemsthatoperateonbothmobileanddesktopdevices.But,dotheseproductspro-videatrueUMsolution?

Multiplemessagingsystemscanresideonasin-gledevicewithoutprovidingaUMexperience.Forexample,thedesktopinterfaceyouusetocomposeandsendemailprobablydiffersfromtheoneyouusetochatwithyourfriendsinanIMsystem.Be-causeofthisinterfacefragmentation,usersmustoftenworkwithmultiplewindowsopenontheirdesktops—oneormoreemailclients,desktoporWebclientsforSkypeandGoogleTalk,andacor-poratevoice-messagingsystemclient.Whenusingamobiledevice,usersareoftenrequiredtoclosethecurrentapplicationorswitchbetweenapplica-tions,limitingthemtointeractingwithonlyonemessaginginterfaceatatime.Consequently,ifyoucan’t seeallofyourmessaging interfaces, you’resurelymissingsomemessages.

SMS/MMSuser

SMS/MMSuserShort message service (SMS)/

multimedia message service (MMS)center

Wireless network

Email user Email user

Email server

IM system Aserver

IM system Auser

IM system Auser

IM system Bserver

IM system Buser

IM system Buser

Internet

Figure 1. A typical stratified communications system. Users can communicate with others using the same system, but they can’t send messages to users on different systems. For example, an SMS user can send a message to another SMS user, but not to an IM system user. Many commercial IM systems can’t communicate with each other. In the figure, IM system A users can’t communicate with IM system B users. The SMS, email, and IM system A and B users might be the same person; however, they must use different devices and interfaces for each system.

42 IT Pro January/February 2010

MOBILE COMMUNICATIONS

UMaimstoreplacetheseseparatemessaginginterfaceswithoutlosingfunctionality.TheUMclientprovidesasingleinboxviewthatincludesmessagesfromdifferentmessagingsystemsinaunifiedlist.TheUMinterfacecouldbeavailableonyourdesktop,laptop,PDA,cablebox,ormo-biledevice.Itcanalsoprovideauserphonebook/directory fromwhichyoucansendanykindofmessagetootherusers,regardlessofthemessag-ingsystemtheyuse.YoucouldsynchronizethisdirectorywitheachofyourUM-capabledevices.

InUM,presenceinformationhelpsdeterminethebestway tocommunicatewithmembersonyour contact list. Presence information can tellboththeuserviewingthelistandtheUMappli-cation which types of communications systems

arecurrentlyavailableforaspecificuser.Thisin-formationleveragesthecurrentsetofmessagingandcommunicationsservicessupportedbyeachdeviceinuse.Presenceinformationcanalsoindi-cateauser’swillingnesstocommunicate.Ifyou’rebusy—say, in a meeting—you can use presenceinformationtonotifyothersthatyoudon’twishto be disturbed. Most IM systems offer suchpresenceinformation,andmanyothermessagingsystemsarealsobeginningtointegratepresencecapabilities.Forexample,Microsoft ismanifest-ing itsUMvision inthetight integrationofad-dress book and calendar information with itsemail and IMclients,using thedisplayofpres-enceinformationthroughoutcommoninterfaces.

Benefits of UM FunctionalityUMhasatangiblevalueproposition.Forthecon-sumermarket, thebusinesscase forUMmightincludethefollowingpossiblebenefits:

• less complexity because consumers deal withonlyonemessaginginterface;

•deviceconvergence,wherebyuserscangetallmessages(email,IM,SMS,andsoon)oneachoftheirdevices;and

•greaterconveniencethroughasinglesign-intoaconvergedinterfaceandaconvergedmessagerepository.

Enterprisecustomersenjoythesesamebenefits,buttheyalsobenefitfromincreasedproductiv-ity (adifficultbenefit toquantify), a convergedenterprise directory, and improved employeecommunications.

Service providers benefit not only from mes-saging revenues, but also from ownership oftheUMportal,whichmeansthatusersseetheservice provider’s logo and ads rather than acompetitor’s. In addition, offering UM sets theserviceproviderapartfromothersthatdon’tofferthisserviceandcanhelpbuildacustomerbaseormaintainloyalty.

Finally,aUMsystembenefitsthesystemadmin-istratorbyprovidingcentralizedmessagesystemadministration capabilities. The system admin-istratorhasgreater controlovermessaging traf-ficbecauseallmessagestraversetheUMserver,rather than multiple separate message servers,whichmightnotallbeunderthesystemadminis-trator’scontrol.Thisalsoprovidesasinglecontrolpointtosupportacentralizedmessagerepositoryformessagebackupand tomeet regulatory re-quirements. A UM system can increase systemsecuritybyreducingtheuseofout-of-band,un-authorizedmessagingsystemsandincreasingthevisibilityofpreviouslyout-of-bandmessages.

Continual updates and changes to deployedmessagingsystems,alongwiththeinevitableap-pearanceofnewmessagingsystems,complicatesthe task of keeping deployed UM solutions uptodate.SuchchangesmightrequirevendorstoconstantlyupdatetheirownUMsystems.Popu-larornewproprietarymessagingsystemsmightbe unwilling to integrate their systems with anexternalUMsolution.Theownersofthesesys-tems might be content with their market shareandseenobenefitinintegratingwithaUMsolu-tionthatcoulddrawcustomers(orinformation)awayfromtheirmessagingportals.

It’sunlikely that any singleUMsolutionwilleverestablishinteroperabilitywitheverypossibletypeofstratifiedmessagingsystem.Fromaprac-ticalperspective,aUMsystem’ssuccessdependsonthewiseselectionofspecificmessagingsys-tems to integrate. From the user’s perspective,thisdecisionhasasignificantimpact;userswill

In UM, presence information helps determine the best way to communicate with members on your contact list.

computer.org/ITPro 4 3

detect the lackofsupport foraprevalentmessaging system and perceive this lackasafunctionalitygap.Becauseconsumersand enterprises have different messagingsystem requirements, the specific needsof your UM solution’s targeted marketshoulddrivethisselection.

IM has become an increasingly im-portant means of communication in theworkplace.1Thus,asuccessfulenterpriseUM solution must support IM capabili-ties. One or more IM systems might al-readybeinwidespreadusewithinagivenenterprise. The proliferation of specificmessagingsystembrands—suchasAOL,MSN, Skype, Yahoo, and Google—com-plicatestheintegrationofIMsystemsintotheUMsolution.EachoftheseIMsystembrands presents its own set of UM inte-gration and interoperability issues. For-tunately, many of these systems alreadyhave, or are now developing, functional-ity to interoperate with other IM systems. ThedesireforinteroperabilityacrossIMsystemshascontributedtothedevelopmentoftheExtensibleMessagingandPresenceProtocol(XMPP).How-ever,manykey IMsystemsstilluseproprietaryinterfacesanddon’tsupportstandards-basedin-terfacespecifications.

UM provides much more than a simplifiedinterface for messaging users. IT professionalsconstantly face new challenges resulting fromtheproliferationofstratifiedmessagingsystems,andUMcanbeanimportanttoolindealingwiththese challenges. Your organization undoubt-edlyhaspoliciestopreventtheuseofunauthor-izedmessagingsystemsand tomaintainofficialrecords. These policies’ effectiveness can varygreatlyacrossandwithinorganizations.Aserver-basedUMsystemcanincreasethewaysinwhichuserscommunicatewhileprovidingmechanismstocontrolandrecordmessagingtrafficthatprevi-ouslybypassedorganizationalcontrols.Youror-ganizationmuststillclearlyidentifythemessagingsystemsauthorized forofficialcommunications.Obviously, UM won’t prevent determined usersfromusingunauthorizedmessagingsystems.

Client- and Server-Based UM SolutionsFigure2showsaclient-basedUMsolution.Inthis system, the client provides a single inter-

facefromwhichtheusercanaccessallthemes-sagingsystems.Theclient-basedUMsolutionaccomplishesthisbyemulatingtheclientfunc-tionality required for each messaging system.The UM client must therefore have the nec-essarycredentials (accountandpassword)andthefunctionality(protocolandserveraddress-es)requiredtologintoeachmessagingsystemserver.Asitsnameimplies,aclient-basedUMsolutionplacestheburdenofintegrationontheclient—thatis,aclient-basedUMsolutionpro-viding access to four messaging systems musthavefoursetsofsign-incredentials,fourmes-sagingservers,fourpathsalongwhichmessag-es can flow, and four source phone books. Aclient-basedsystemmighthavetohandlemoreclient-to-networktraffic(multiplesign-ins,reg-istrations, connection maintenance methods,presenceinformation,andsoon)thanaserver-basedUMapproach.

Figure 3 shows a server-based UM solution.Unlikeaclient-based solution, the server-basedsolutionneedsonlyonesetofcredentialsatthemessaging client for accessing the UM server.TheUMserver,whichmaintainsthecredentialsand other information required for server-to-serverinteroperability,interactswithanyexternalmessaging systems. All messaging traffic fromthe UM client traverses the UM server in the

SMS/MMSuserSMS/MMS

center

Wireless network

UM user(client based)

Email userEmail server

IM system Aserver

IM system Auser

IM system Bserver

IM system Buser

Internet

Figure 2. A client-based unified messaging system. In this system, a single client must interact with multiple messaging servers using interfaces that are unique to each messaging system.

44 IT Pro January/February 2010

MOBILE COMMUNICATIONS

network.Therefore,theUMserveroffersacen-tralizedmessage-managementandstoragecapa-bilitythatcanprovidevisibilityandsomelevelofcontrolovermultiplemessagingsystems.

Corporate entities have several strong busi-ness- and regulatory-based requirements driv-ingtheneedforamorecentralizedcapabilitytomanage and control messaging traffic. Thus, aserver-basedUMmodelwillprobablymostben-efitenterpriseapplications.

In all likelihood, client-based, server-based,andhybrid (usingbothclient-andserver-basedcomponents)UMsystemswillbecomeavailableintheforeseeablefuture.

What’s Available NowNowfortherealitycheck:there’snosingleUMsystemunderdevelopmentthatwilltakeoverthemessaging market. Mobile messaging systemssuchasSMSandMMSareexpandingintheUS(USuserssentmorethan1trillionSMSmessag-esin20082)andwillremainasignificantforceinthemobilemessagingmarketforyearstocome.Inaddition,wecan’tassume that thevarietyofemail and IMsystemswilldecrease.Newmes-saging systemswill likely continue tobedevel-opedanddeployed.

Untilrecently,manycorporatemessagingsys-temswererelativelysimpleandcenteredonemailcommunications.Althoughemail-basedsystems

are being extended to mobile devices (forexample, using Microsoft Exchange onBlackberry devices), these solutions don’tprovide a fully converged mobile messag-ingexperience.UsersmightbeabletosendandreceivebothemailandSMSmessagesfromamobiledevice throughasingle in-box;however,theyoftencan’tdothesamefrom their laptop computer, cablebox,orWeb page. Relatively few PC-based sys-temssupportunifiedIM,SMS,MMS,andvoicemail messaging. A hallmark of trueUMcapabilitywillbe full convergenceofmessaging systems across different mes-sagingdevicetypes.

SeveralproductsavailablenowadvertiseUMcapability.Eachoftheseproductsap-pearstofocusoncombinationsofdifferentmessaging systems, devices, and markets.A detailed analysis of the differences be-tween these products is beyond this arti-

cle’sscope.Pidgin (http://pidgin.im/about) and Meebo

(www.meebo.com/about) are examplesof client-basedUMsolutions thatprovideaunifieduserinterfacewithconnectivitytomultiplepopularIMsystems.BothareprimarilyforcomputerdesktopenvironmentsusingaclientorWebpage.Fring(www.fring.com)isasimilarclient-basedUMso-lutionthatwasdevelopedformobiledevices.

Alcatel-Lucent’sRichCommunicationsMan-ager, Microsoft’s Exchange Server, and Cisco’sUnity are examples of more sophisticated UMsolutions that integratemultiplemessagingandcommunicationssystemsthroughaunifiedmes-saginginterfaceusingnetwork-basedUMserversorotherspecializednetwork-basedcomponents.

Future Directions UM work is proceeding across two fundamen-tallydifferentpaths:vendor-specificproprietaryimplementations and open standards-basedimplementations.

Vendors will continue to develop proprietaryserver- and client-based UM solutions. Many ofthesesolutionswillleveragesuitesofservicesthatarealreadyinwidespreadusewithinanenterpriseortheconsumermarket.AlltheUMsystemsI’vementionedareproprietarytosomedegree.TheseproprietaryUMimplementationswilllikelyexhibitanincreasinglevelofsophistication,functionality,

SMS/MMSuserSMS/MMS

center

Wireless network

UM user

Email userEmail server

IM system Aserver

IM system Auser

IM system Bserver

IM system Buser

InternetUM

server

Figure 3. A server-based unified messaging system. The UM user and client communicate only with the UM server; the UM server interacts with all other messaging servers.

computer.org/ITPro 4 5

and interoperability. Server-based UM solutionswillcontinuetobefocusedonenterprisesolutions;UMsolutionstargetingconsumerswilllikelyonlybeoffered throughmediumto largeservicepro-viders.Client-basedUMsolutionsrequiringlittleornospecializednetworksupportwillcontinuetogainshareintheconsumermarket.

AgreatdealofworkseekstodefineUMfunc-tionalitybasedonopenstandards.Forexample,Converged IP Messaging is a Session InitiationProtocol(SIP)-centricapproachtoUMmanagedbytheOpenMobileAlliance(OMA).CPM’sstat-edgoalistodefineanenabler“toallowforboththe consolidation of present and the creationof future interpersonal interactive multimediacommunication services which accommodatedifferentuserexperiences suchasdeferredandImmediate Messaging, session-based messag-ing,andhalfduplex/fullduplexconferencing.”3

TheCPMeffort alignswithother standards toincludeOMAstandards aswell as the IPMul-timediaSubsystem(IMS)specificationsdefinedby the Third-Generation Partnership Projects(3GPPand3GPP2.)3

Enhanced messaging (EM) is another ex-ample. It’s a SIP-centric approach focused onmessaging for mobile 2G devices defined bytheCTIA’sWireless InternetCaucusEnhancedMessaging Action team. EM leverages someOMA standards work, but it focuses on inte-grating mobile messaging with IP-based mes-sagingsystemsacrossmobilecarriers(seewww.ctia.org/business_resources/wic/index.cfm/AID/11506).

Both CPM and EM define requirements andstandards that are moving the industry towardan open, comprehensive UM solution. There’shope that UM will indeed encourage industrymovementtowardopenstandardsandincreasedinteroperability,andawayfromafragmentedandproprietarymessagingfuture.

J ackSantosobservesinCIO Magazine:“UC[unifiedcommunications,which includesunified messaging] is still a vision and

long-termstrategy—reallytherecognitionofanoverall trend with communications … vendorstaketheUCmonikerandrunwith it (anysur-prises there?) tosellproducts thatmayormaynotbereadyforprimetime.Therealityisuni-

fiedcommunicationswillonlyberealwhenap-plications are developed based on the underly-ingtechnologies—andsofartherehasbeenno‘killerapp.’”4

This is an important perspective. As UM-related development and standards mature,moresophisticatedUMproductswillappearonthe market. Investigate and assess these emerg-ing UM capabilities with a critical eye, and en-sure that applications touted as providing UMcapabilitiesdoinfactgivemeaningfulvalueandROI.LearnthecapabilitiesofavailableUMsys-temssoyoucanchoosetherightsystemforyourorganization.

Inthemeantime,continuemanagingyourexist-ingmessagingsystems.Ensurethatyouknowtherisksofusingstratifiedorunauthorizedmessagingsystems.AsanITprofessional,it’syourjobtode-velopandenforceclearpoliciestoincreaseaware-nessandreduceyourvulnerabilities.Butasauser,youhavealotofmessagingsystemstomanagebe-foretheperfectUMsolutioncomesalong.

References 1. E.Isaacsetal.,“TheCharacter,Functions,andStyles

of Instant Messaging in the Workplace,” Proc. Conf. Computer-Supported Cooperative Work (CSCW), ACMPress,2002,pp.11–20.

2. Y.Zhangetal.,“ANovelMethodfortheShortMes-sageorMultimediaMessageSynchronization,” Proc. Int’l Multi-Conference Computing in the Global Information Technology,IEEECSPress,2006,p.75.

3. Open Mobile Alliance, “Converged IP MessagingArchitecture Draft Version 1.0,” OMA-AD-CPM-V1_0-20080418-D,Apr.2008.

4. J.Santos,“UnifiedCommunicationsandtheCIO,”CIO New Zealand, 14 Apr. 2008; http://cio.co.nz/cio.nsf/tech/BAC0A77B98F90374CC257422001A5C28?Opendocument&HighLight=2,unif ied,communications.

Clinton M. Banner is a business development manager for IP- and IP multimedia subsystem-based communica-tions systems at Alcatel-Lucent and a doctoral student in technology management at Indiana State University. As a chief warrant officer in the US Army, he participated in multiple combat and humanitarian operations in the Mid-dle East, Africa, and the Balkans. Banner has an MS in technology systems from East Carolina University. He’s a senior member of the IEEE. Contact him at clint.banner@alcatel-lucent.com.

For access to more content from the IEEE Computer Society, see computingnow.computer.org.

This article was featured in

Top articles, podcasts, and more.

computingnow.computer.org