SIP TRUNKING 101: A Primer

Transcription

1 SIP TRUNKING 101: A Primer AUGUST 2012

2 KEY BENEFITS Cost reductio i the order of 30-50% Icreased flexibility, as umbers are o loger tied to locatios. Cost effective disaster recovery capability Support for widebad audio ad video I syc with developig requiremets for uified commuicatios ad collaboratio Eterprise commuicatios have bee rocked by two major developmets over the past decade. O the etwork side, legacy etwork services like PRI ad frame relay have give way to all-ip based alteratives. O the premises side, traditioal circuit switched or TDM-based PBX systems have bee overtake by hybrid or full voice over IP (VoIP) solutios ad the fuctioality of those systems is ow beig ehaced by uified commuicatios (UC). Capitalizig o these treds, eterprise users are icreasigly movig to SIP trukig services to reduce cost ad icrease reliability while opeig the door to ehaced fuctioality. Accordig to a recet study of 500 eterprise commuicatios buyers coducted by The SIP School, 55% of compaies are ow usig SIP trukig services ad the percetage of compaies reportig they are testig the service jumped to 26.0% from 16.6% a year earlier. The rapid shift to SIP trukig has also created more tha its share of cofusio. Each service provider will typically portray its SIP trukig offerig as the defiitive way that the service is offered- the reality is much differet. There are sigificat differeces i the way SIP trukig services are deployed, how they are priced, ad the features ad fuctios they ca deliver. Eterprise users will eed to have a clear picture of how they see their etworks evolvig to choose the most effective parters for their SIP trukig iitiatives. To be sure, SIP trukig services ca meet the core reliability requiremets of the eterprise. Ulike early cosumer-orieted VoIP services, SIP Trukig ca provide a secure, reliable, eterprise grade voice service that ca sigificatly reduce cost. Importatly, orgaizatios eed ot wait util they upgrade their TDM PBX systems to take advatage of the cost savigs ad icreased flexibility SIP Trukig ca afford. Further, as those voice etworks evolve to uified commuicatios, SIP trukig provides exactly the type of flexible commuicatios services that will be essetial i that eviromet. The purpose of this paper is to take a step back ad look at the overall market for SIP trukig services, describe the major areas where they differ, ad to provide a better uderstadig of the alteratives ad how those elemets should be factored ito the buyig decisio. Make o mistake about it, the migratio to SIP trukig is uderway (ad with good reaso), but there are importat differeces that must be uderstood to esure a good outcome. TDM to VoIP The migratio of the log distace portio of the telephoe etwork to IP bega i the late-1990s, as carriers foud that it was far more cost effective to carry voice calls over a IP backboe tha through a traditioal etwork of fixed sized, dedicated chaels. The iterface to the customer cotiued to use legacy TDM techologies like T-1 ad Primary Rate Iterface (PRI) that were supported o traditioal digital PBX systems. However, oce those calls hit the public etwork they were coverted ito packet form ad forwarded over a IP core. Whe the call arrived at the last cetral office, it was agai coverted back to a T-1 or PRI format (or to a basic aalog iterface) ad delivered to the recipiet. As eterprise customers bega migratig their PBX systems to IP-based alteratives, the TDM-based etwork access coectio became a aomaly i the path. What s more, it was also a iflexible choke poit i what was otherwise a ed-to-ed IP-based voice coectio. However, trasitioig to a ed-to-ed VoIP eviromet would call for a more flexible ad fuctioal mechaism for settig up coectios ad activatig features. This is where the power of SIP ca be see. Rather tha the oe-size-fits-all approach of the traditioal telephoe etwork, SIP sigalig allows ay type of real time coectio, with ay required bit rate, to be established through a 1

3 flexible IP etwork. What s more, SIP has features whereby the ed poits ca advertise ad egotiate the parameters of the coectio icludig the voice or video ecodig based o the rage of optios each ca support. So as eterprises move to the rich commuicatios eviromet defied by UC, SIP provides a sigalig mechaism that is developed specifically for that type of eviromet. SIP Trukig Cofiguratios I its simplest form, SIP Trukig is a alterative to traditioal T-1 or PRI etwork coectios betwee a eterprise PBX ad a service provider. Rather tha takig a Mbps chael ad dividig it ito 23 or 24-fixed size 64 Kbps voice chaels, SIP trukig uses a IP-based lik of whatever size to coect the eterprise s telephoe system to the service provider s etwork. That access lik ca be dedicated to SIP trukig or it ca be shared with other IP applicatios. I deployig SIP truks, there are a umber of cofiguratio optios available. First, SIP truks ca be deployed at each compay locatio much the way traditioal T-1 or PRI truks are used today. The other optio would be to deploy all of the SIP truks at a sigle data ceter, itercoect all of the sites over a IP backboe, ad route all exteral calls through that data ceter for access to the public etwork. The advatage of that cetralized trukig approach is that larger truk groups are iheretly more efficiet ad you ca typically use fewer truks to support the total volume of calls; if the locatios are i differet time zoes, those savigs ca be eve greater. Of course, cetralizig all etwork access itroduces a sigle poit of failure, so may orgaizatios deploy SIP truks at two or more locatios (possibly icludig a disaster recover site) to esure cotiuous etwork access. To set up a call (or more specifically a sessio ) a series of SIP sigalig messages are exchaged betwee the PBX or UC system ad the etwork. Whe the sessio is i place, the voice or video is forwarded i a series of packets addressed to the other party. Those packets are trasported over the IP backboe ad at the far ed they ca be delivered over aother SIP truk or passed through a gateway to be delivered over a traditioal aalog or TDM-based coectio. While that descriptio would be true of all SIP trukig services, there are a umber of importat differeces i the way the service is implemeted ad the features that ca be offered. Those differeces will have a impact o both the total cost of owership (TCO) as well as the services ad cofiguratios that ca be supported. Iteret Backboe Optios Iteret providers offer two types of IP services: basic IP ad Multi-Protocol Label Switchig (MPLS). Basic IP provides a best effort trasport service where packets may be delayed or dropped radomly if they ecouter cogestio i the etwork. MPLS is a higher priced IP service where the operator will provide service level agreemets (SLAs) specifyig worst-case performace for delay, packet loss, ad jitter (i.e. the maximum variatio i delay from packet to packet). As VoIP uses the User Datagram Protocol (UDP) to trasport voice packets, there is o recovery from dropped packets. The reaso for this is that if the seder were to resed a voice packet (or ay packet carryig real time iformatio), it would arrive too late to have ay relevace to the voice stream. If too may packets are lost, the quality of the voice trasmissio will be degraded. The possibility of packet loss has led may SIP trukig providers to tout the ecessity of usig the more expesive MPLS service to esure adequate voice quality. However, there is a growig body of evidece that suggests this is a uecessary cost. Whe cosumer VoIP services like Voage were first lauched, the IP service providers were strugglig to keep pace with the explodig traffic growth i their etworks. As a result, voice quality did suffer to some extet leadig to a bad reputatio for VoIP services as a whole. Fast forward a few years ad we see a completely differet picture for basic Iteret service. Prices for higher ad higher capacity backboe routers have plummeted, ad the move to wave divisio multiplexig (WDM) o fiber optic trasmissio systems has allowed the IP etwork operators to cost effectively icrease the capacity of their etworks. The result is that packet loss ad delay performace cotiues to improve to the poit that may questio whether a MPLSbased service is worth the extra cost. 2

4 The other advatage of usig broadbad Iteret service is that the SIP trukig service ca be tured up much faster. MPLS services must be desiged ad provisioed for each customer idividually leadig to istallatio itervals that are measured i weeks or moths. Virtually every compay has basic Iteret service istalled for web access ad other applicatios, ad if there is capacity available over those liks, SIP trukig services ca be tured up i a matter of days. May customers who have istalled SIP truks i that fashio o a trial basis have foud the performace of basic Iteret service to be more tha adequate ad cotiue to deploy SIP truks over those services. Oe other factor that has cotributed to the move to basic Iteret services is improved voice codig ad packetloss maskig optios. VoIP systems are desiged i aticipatio of the fact that packets will be lost. As a result, VoIP receivers icorporate buffers ad techiques to mask the impact of lost packets. Additioally, the low (ad decreasig) cost of badwidth, coupled with predictable ad ifrequet Iteret trasit delays create a viable architecture ad strog ecoomic case for routig real-time media applicatios that still deliver high QoS over the public Iteret. This avoids the eed to deploy expesive, parallel coectivity over the pre-existig low cost broadbad coectio. Premises Equipmet Compatibility: Gateways ad Sessio Border Cotrollers (SBCs) There is premises equipmet that is required to coect to a SIP trukig service. The specific requiremets are based o the type of telephoe system i use ad the optios are typically a gateway or a sessio border cotroller (SBC). Coectig a traditioal TDM-based PBX systems to a SIP truk will require some type of gateway device; the truk iterfaces o those systems are typically limited to aalog, T-1, ad PRI. It is importat to ote that you eed ot defer your trasitio to SIP trukig based o a legacy PBX. Gateways take oe of those traditioal iterfaces ad covert it ito a VoIP/SIP iterface. Gateways are available from compaies like Adtra, AudioCodes, ad NET. ItelePeer ca supply a list of gateway devices that are tested ad certified to work with its services. If you have already made the shift to a IP PBX or UC solutio for voice, those systems ca coect directly to a SIP truk, however you will eed to be cogizat of the compatibility issues. Like ay data protocol, the SIP stadards describe a wide variety of optios, which meas that ot all SIP-capable devices ad services ca fully iter-operate. Fortuately, SIP trukig ivolves far fewer features tha what would be foud o a multi-butto SIP hadset istalled behid a IP PBX. SIP hadsets will eed to support hold, coferece, trasfer, multiple lie appearaces, message waitig lights ad the rest of the feature set typically foud o a moder PBX system. Eve though the feature set with a SIP truk may be more limited, you would be wise to search out SIP trukig providers that have bee certified to iteroperate with all of the various PBX ad UC systems you have deployed. While a IP PBX or UC system may be directly compatible with the SIP trukig service, some customers choose to istall a sessio border cotroller (SBC) betwee the telephoe system ad the SIP trukig provider. SBCs ca provide a umber of security fuctios like protectio from deial-of-service (DoS) attacks, toll fraud via rogue media streams, etwork topology maskig, ad malformed packet protectio. SBCs ca also traslate betwee differet voice codig systems ad icompatible SIP sigalig implemetatios. SBCs are available from leadig compaies like AcmePacket, AudioCodes, Avaya, Cisco Systems ad Sous. ItelePeer ca supply a list of SBCs that are fully tested ad certified to work with its services. 911, E911 ad Nomadic E911 Capability The other importat (ad ofte overlooked) elemet i SIP trukig is compatibility with Ehaced 911 (E911) services. The 911 emergecy call service operates o a special etwork that was desiged to work i cojuctio with the traditioal circuit switched telephoe etwork. Whe a user dials 911 the call is routed to the geographically appropriate Public Safety Aswerig Poit (PSAP). Where basic 911 provides the telephoe umber of the callig party to the PSAP aget, E911 does a database dip ad provides the locatio as well; the availability of E911 capability is depedet o the subscriber s local PSAP. Needless to say, the ature of IP-based services adds aother level of complexity to that equatio. Mobile devices preset a particular challege i E911 services. UC cliets ruig o tablets or laptops ca be highly mobile as users may roam throughout a eterprise campus, trasitio betwee telework locatios (e.g. a home office, 3

5 remote office, the local Starbucks, etc.), or may eve be travelig aroud the world. I order to appropriately establish the locatio of these users at the time of a emergecy call, a dyamic locatio idetificatio service will be required. I lookig for potetial SIP trukig providers it is essetial to cofirm that the provider ca support 911 ad E911 service at all locatios as well as offer solutios for mobile or omadic UC users. Further, you will eed to cofirm the specific addresses (icludig floor or buildig umbers) associated with each DID umber that is passed to the PSAP. Fially, give the potetial life-ad-death ature of those calls, it will be importat to uderstad the various levels of backup the provider has implemeted to esure that those calls are delivered i a timely fashio. SIP Pricig Plas ad Cost Advatages There are a umber of differet pricig plas offered for SIP trukig services, which will directly impact TCO. Amog the pricig elemets ad optios you will fid are: Access Coectio: I virtually all cases the basic coectio betwee your office ad the SIP trukig provider s poit of presece will be billed separately. As we are essetially talkig about a Iteret access coectio, there are a umber of differet optios. For small locatios or telecommuters, DSL or cable modem services could be used. Larger locatios ca be served with multiple T-1 (1.544 Mbps) or T-3 ( Mbps) dedicated liks. For eve higher capacity access, very cost effective metro Etheret ad wavelegth services are available. Those access liks ca be used to support SIP trukig services exclusively or SIP truks ca share a access coectio with web access ad other data services. Sizig the access lik appropriately will be critical to success. Agai, it is importat to iclude the IP overhead, so a 64 Kbps (G.711) chael requires about 90 Kbps ad a 8 Kbps (G.729a) chael requires about 30 Kbps. If video calls are to be carried as well, you will eed to ascertai the required capacity per chael from the video supplier. Callig Charges: As with traditioal telephoe services, there is ofte a cost per miute for calls placed over the SIP truk. Cost per miute is typically lower tha with traditioal callig services due to the advatageous tariff ad tax rates applied to IP calls. If you ited to be placig video calls as well, it is importat to determie how those calls will be billed. ItelePeer offers its customers the optio of choosig such a miute of use (MOU)-based billig model. SIP trukig providers are ow addig features like those foud i traditioal T-1 ad PRI services like icluded local callig ad toll free service or the ability to trasfer or reroute calls based o time of day or i the evet of a disaster, facilitatig the PRI to SIP truk price compariso. Simultaeous Calls ( Call Paths, or Ports ): May SIP trukig providers base their pricig i part o the maximum umber of simultaeous calls or ports the service will support. Oe flexibility advatage i SIP trukig is that you ca purchase the exact umber of ports you require. I leasig traditioal T-1 or PRI etwork access, you are forced to purchase iflexible budles of 23- or 24-voice truks. Oe feature that ca add to the cost effectiveess is port sharig, which allows idle ports at oe locatio to be used for calls at other locatios. For example, if you have 10 ports cofigured at each of your offices i New York, Atlata, ad Los Ageles, but o oe is usig the ports i Los Ageles (e.g. early i the morig), those 10 ports are available to support calls at the New York or Atlata locatios. That sceario assumes there is sufficiet capacity o the access liks i New York ad Atlata to support those additioal calls. ItelePeer offers its customers the optio of choosig such a port-based billig model. Budled Services: Some SIP trukig providers are goig to a simpler pricig structure based o the umber of users. Rather tha tryig to determie the exact umber of truks required based o a voice traffic study (i.e. Erlag study ), local ad log distace service ca be priced at a flat mothly rate per user. I some cases those budles ca be priced like a flat-rate SIP port that is shared by a umber of users. Those budled pricig arragemets will typically have a fixed premium to support video as well as voice calls. ItelePeer offers both user- ad port-based pricig optios that iclude local ad log distace callig, as well as a allocatio of toll free ad local DID phoe umbers, port-is ad directory listigs. 4

6 The ROI for SIP Trukig I today s ecoomic climate, there is a real eed to establish a soud ROI for techology iitiatives. A recet white paper published by Uified IT Systems illustrates the potetial savigs for a 5,000 employee orgaizatio migratig from TDM to SIP trukig ad fids those savigs to be i the order of 30% to 50%. The impact ca be see i a umber of areas. Truk Aggregatio: The majority of eterprise customers deploy SIP truks i cojuctio with a strategy of cetralizig all of their voice etwork access at oe or more data ceters. Distributed sites are typically itercoected with a MPLS virtual private etwork, ad the cost of the additioal capacity to carry the voice traffic to the data ceters is miimal. Oe of the basic priciples of traffic egieerig is that oe large group of truks hadles traffic more efficietly tha several smaller groups, ad that reductio i the umber of truks (or call paths) ca be o the order of 25%. A additioal efficiecy from cetralized trukig ca be see whe locatios are scattered across several time zoes. The busiest hours for telephoe usage geerally occur aroud 10 to 11:00 AM ad 2 to 3:00 PM local time. With locatios i differet time zoes, those busy hours will occur at differet times reducig the total umber of call paths required to support busy hour traffic peaks. Flexibility: Where T-1 ad PRI access arragemets require that truks be purchased i buches of 23 or 24 voice chaels, with SIP trukig a orgaizatio ca order exactly the umber of truks it requires. To estimate the savigs, you ca assume a mothly savig equivalet to half the cost of a additioal PRI. Those savigs ca be further ehaced if the orgaizatio has highly seasoal callig patters. Retailers have traffic peaks prior to holidays ad tax preparatio compaies peak prior to April 15. SIP trukig services typically allow ports to be added or deleted quickly. Aggregated Access: For each T-1 or PRI access coectio, the customer has to ret a Mbps dedicated lie to the carrier s servig poit. With data access there are cosiderable ecoomies of scale (i.e. the higher the access capacity the lower the cost per bit). Usig Metro Etheret or other high capacity access optios, access costs ca be cut by as much as 80%. Network Features: SIP trukig services ofte iclude services that are separately charged for o PRI services. Features like call trasfer may cost $50 per truk per moth, makig a SIP optio far more advatageous. Bill Processig ad Admiistratio: Orgaizatios sped cosiderable time ad effort processig ad auditig telephoe bills, trackig usage, ad settig up iteral chargebacks. SIP trukig providers may offer flat rate budled service plas effectively elimiatig the admiistrative overhead of the traditioal phoe bill. Further, havig all of the etwork access termiated at oe or a small umber of sites rather tha scattered to all etwork locatios also simplifies the admiistratio ad maiteace. What s Next for SIP Trukig? At the outset, SIP trukig is beig see as a lower cost, more flexible alterative to traditioal T-1 or PRI etwork access to support basic voice telephoy. However, to look at SIP trukig as a apples-to-apples swap for those legacy services would be missig a big poit about SIP. With the advet of UC, the stadaloe ature of voice service is chagig. I a UC eviromet, voice is just oe of a umber of commuicatios optios that will be available to the user. Presece capability will allow colleagues to determie if a party is available for a commuicatios sessio ad what type (i.e. text, voice, video, web collaboratio). The caller ca the request the coectio with a sigle click (or escalate the sessio from oe commuicatios modality to aother) ad their UC system will geerate the required strig of SIP messages to establish a poit-to-poit or coferece coectio. The task of mergig all of those various commuicatios capabilities ito a sigle shared iterface goes far beyod the ability of traditioal trukig iterfaces ad sigalig protocols. The basic desig of SIP evisioed this type of rich commuicatios eviromet ad icorporates the tools to establish a variety of sessios, support multiple media 5

7 types, ad eve egotiate the types of ecodig that will be used. This will allow for such fuctios as upgradig a text coversatio to a voice or video call, or to itegrate caledar ad coferecig capabilities so a user ca joi a coferece by clickig a sigle butto. Probably the most importat additio to SIP is SIMPLE or SIP with IM ad Presece Leveragig Extesios; a similar set of capabilities exists with XMPP (the Extesible Messagig ad Presece Protocol). As more orgaizatios move to UC-based commuicatios solutios, they will eed to exted those rich commuicatios capabilities to suppliers, parters, ad other outside parties. UC federatio, or the ability to lik UC fuctioality betwee differet platforms i differet orgaizatios, will be key, ad tools like SIMPLE ad XMPP will provide the essetial sigalig elemets required to brig that about. The other major developmet is cloud-based deploymets, ad we already have dozes if ot hudreds of providers offerig cloud-based IP PBX ad UC solutios o virtually every platform available. As users move some or all of their users to these cloud-based offerigs, SIP trukig will still be a elemet i the solutio as the cloud providers have bee amog the first to make the chage. Coclusio Eterprise commuicatios has etered a ew phase with the advet of uified commuicatios. Users will ow be able to itermix their real time, ear real time, ad asychroous commuicatios ad access a wide array of collaboratio tools i ew ways that spur productivity ad speed decisio makig. Whether we are lookig at traditioal office commuicatios or the expadig rage of optios i the cotact ceter, UC is havig a major impact o how people will commuicate ad collaborate. That type of rich commuicatios will call for a ew set of tools with the ability to grow ad expad to support a cotiuously evolvig set of capabilities. SIP trukig provides just such a capability, ad oe that ca reduce TCO i the short term while providig the foudatio o which these ew capabilities ca be deployed as time goes o. ABOUT THE AUTHOR Michael F. Fiera, dbr Associates, Ic. mfiera@dbrassociates.com Michael Fiera is Pricipal at dbr Associates, a idepedet idustry aalyst ad cosultig firm. Alog with providig cosultig assistace to carriers, equipmet maufacturers ad ed-user orgaizatios, Michael is a frequet speaker at idustry cofereces icludig IterOp, Eterprise Coect, ad the Iformatio Week 500. He has published over 300 articles as well as umerous white papers ad market reports. His blogs appear regularly i Iformatio Week, NoJitter.com, UCStrategies.com, ad the Voice Report. Michael is a member of the Society of Telecommuicatios Cosultats ad he has a Masters Degree from the J. L. Kellogg Graduate School of Maagemet at Northwester Uiversity. Corporate Headquarters 177 Bovet Suite 400 Sa Mateo, CA T: F: ItelePeer is a leadig provider of o-demad, cloud-based commuicatios services that deliver high-quality HD voice, HD video ad uified commuicatios for busiesses ad cotact ceters. ItelePeer eables uified commuicatio ad collaboratio (UCC) solutios from every major vedor with its SIP services ad Fluet Federatio-as-a-Service, providig eterprises with a ubiquitous user experiece ad seamless trasitio to the clarity, reliability ad umatched quality of IP commuicatios served from ItelePeer s Cloud platform. For more iformatio visit: Copyright 2014 ItelePeer. All Rights Reserved. ItelePeer, the ItelePeer logo, CloudWorx, Media Peerig Grid, SuperRegistry ad AppWorx are trademarks of ItelePeer. 0812