www.tekelec.com | 1SIP Signaling Router Application HandbookThe exclusive guide for solving next-gennetwork challenges with SIPUpgrade Your Next-Gen Network TodayThe intent of this handbook is to provide operators with a useful reference guide for how they can use a SIP Signaling Router (SSR) to solve many of their next-generation network challenges.Tekelec, a global leader in core multimedia session control, mobile messaging and network intelligence, ensures scalable, secure and highly available communications. The companys market-leading signaling solutions enable the interworking of diferent network applications, technologies and protocols, providing a smooth transition to next-generation networks. Tekelec has more than 20 ofces around the world serving customers in more than 100 countries, with corporate headquarters located near Research Triangle Park in Morrisville, N.C., U.S.A.For more information please call 888.628.5521 or +1.919.460.5500Visit our web site at www.tekelec.comThe information presented is for demonstration purposes only and is not intended to represent any particular company. Any similarities are purely coincidental. Actual performance results depend on particular network confgurations, capacity and other technical requirements.IntroductionThe benefits of next-generation, voice over Internet protocol (VoIP) networks are compelling for operators worldwide. Deployments cut across all types of telecom operators from the largest incumbents to the smallest regional players. Providers see VoIP and session initiation protocol (SIP)-based services as an opportunity to cut their operating expenses and boost their bottom line with new revenue. Delivering VoIP and SIP services to consumer and enterprise customers enables providers to expand their subscriber base. And, SIP facilitates the interworking of real-time applications with voice and video to create new, multimedia services. However, as VoIP and SIP trafc and applications grow, so do the requirements placed on the network to support them. Many operators are discovering that their current next-generation networks (NGNs) are based on an out-dated, voice-centric, softswitch architecture, which does not support multimedia services, access independence, backward network compatibility or network growth. www.tekelec.com | 3Table of ContentsIntroduction 3The Challenge 4SIP Signaling Router 4Use Case 1: Enhanced Application Server Selection 5Use Case 2: SIP Trunking 9Use Case 3: SIP Number Portability 14Use Case 4: Centralized SIP Routing 18Use Case 5: Specialized SIP Proxy 22Summary 26About Tekelec 27Appendix-1: Acronyms 27 The ChallengeUnlike signaling system 7 (SS7) and Internet protocol multimedia subsystem (IMS) networks, which are hierarchical, there is no separate signaling and session control layer at the core of the NGN. From a signaling perspective, each NGN network element must handle all application-layer related tasks such as routing, traffic management, redundancy and service implementation. All possible routes must be defined at each node, creating a logical, mesh-network routing architecture. Expanding the NGN without a framework that ofoads session and signaling tasks from the edge elements is complex and costly. SIP Signaling RouterTekelecs SIP Signaling Router (SSR) solution, a SIP proxy with enhanced routing capabilities, creates a signaling and session control framework for NGNs by implementing SIP routing functionality in the core network. The SSR enhances routing capabilities and increases service and network fexibility by relieving endpoints of session management duties. The resulting architecture allows the NGN to grow systematically in response to increasing demand for VoIP and multimedia services. The SSR solution is based on 3rd Generation Partnership Project (3GPP) specifications and ofers adaptations for interworking with non-3GPP-compliant IP environments. It provides seamless interworking and creates an evolution path to future technologies such as IMS, long term evolution (LTE) and WiMAX.This handbook explores five use cases that demonstrate the applications and associated benefits of deploying Tekelecs SSR in NGN networks. They include: |r|.rcoJ .pp||c.t|cr so.vo. so|oct|cr S|| t.Jrk|rc S|| rJnbo. pc.t.b|||tv ort..||.oJ S|| .cJt|rc Spoc|.||.oJ S|| p.cxv4 | SSR Application Handbookwww.tekelec.com | 5Use Case 1: ENHANCED APPLICATION SERVER SELECTIONProblem: The operator, Company A, provides VoIP services to small enterprise customers, using a SIP enterprise application server (AS) and SIP phones. The SIP AS provides voice features such as find-me, follow-me and simultaneous ring. Each subscriber must be identified and registered on the SIP AS platform. Prior to shipping, Company A configures each SIP phone with the address of the SIP AS, which is voipsvc.CompanyA.com. The SIP phone uses this address for registration and to make voice calls. Company A IP NetworkVoIP ASHosting SubscriberA through ZAddress =voipsvc.CompanyA.comvoipsvc.CompanyA.comvoipsvc.CompanyA.comvoipsvc.CompanyA.comvoipsvc.CompanyA.comvoipsvc.CompanyA.comvoipsvc.CompanyA.comFigure 1: Subscribers are identifed and registered on the SIP AS platform.6 | SSR Application HandbookCompany A IP Networkvoipsvc1.CompanyA.comvoipsvc2.CompanyA.comvoipsvc3.CompanyA.comvoipsvc4.CompanyA.comSub A-F Sub G-M Sub N-S Sub T-ZCompany A has developed a solid reputation for its service quality, and its subscriber numbers have grown significantly. To support current and future growth, the company deploys three additional application servers, each with its own address. Subscribers are now distributed among four application servers. Figure 2: How can Company A easily map subscribers to the application servers?www.tekelec.com | 7This new configuration poses a number of problems. With four application servers in the network, how does the SIP phone know which AS to request? And, since the SIP AS address is configured on the SIP phone, each time a customer is assigned to another application server, the address programmed on the SIP phone must be reconfigured. From a technical perspective, the problem is the result of a tight coupling between the SIP endpoints the SIP phones and the SIP AS. Any changes to the physical network, such as adding a new application server, have a direct impact on the way the SIP phones access a service. As a result, complex provisioning is increasing operational costs, and quality of service is being impacted by service disruptions due to provisioning errors. Company A needs a solution that will allow the company to: V.r.co c.c.t| .|t|cJt s.c.|||c|rc oJ.||tv c| so.v|co V.ko c|.rcos tc |ts .pp||c.t|cr so.vo. .ss|crnorts without reconfiguring the phones that are already in service.solution:Company A deploys the SSR solution in its network to shield the endpoints from changes in the physical network. Through a process called abstraction, the phones are decoupled from direct knowledge of the complex and changing network. The SIP phones just have to be configured with a single abstract address voipsvc.CompanyA.com. Endpoints send requests to the SSR, which resolves the voipsvc.CompanyA.com address to the appropriate SIP AS platform and routes the request to that platform. Since the endpoint only deals with an abstract view of the network, it is not impacted by changes in the physical network such as adding a new application server. Regardless of changes in the SIP AS topology, the address on the SIP phone remains the same, and no reconfiguration is necessary. 8 | SSR Application HandbookBenefits:By deploying the SSR solution, Company A: .o.tos . |ox|b|o ..c||toctJ.o |.oo c| orJpc|rt constraints. S.vos c.p|t.| ccsts bv s|np|||v|rc sJbsc.|bo. management and maximizing the efficiency of application servers through load sharing and fexible subscriber management. .r oxp|c.o J||o.ort bJs|ross ncJo|s sJc| as using third-party, hosted services. .o.tos . |cJrJ.t|cr |c. nJ|t|noJ|. so.v|cos Sub A-F Sub G-M Sub N-S Sub T-ZRequest to voipsvc.CompanyA.comForward the request to correct AS platformwhere Nick is assignedConsult internal routingpolicy A numberdirected routingNickvoipsvc1.CompanyA.comvoipsvc2.CompanyA.comvoipsvc3.CompanyA.comvoipsvc4.CompanyA.comSIP Signaling RouterFigure 3: Endpoints are shielded from changes in the physical network.www.tekelec.com | 9Company BPOP POP POPLocal Network 2Local Network 3Local Network 4Local Network 1POPPBXPBXUse Case 2: SIP TRuNkINgProblem: Company B is a long-distance (LD) operator that provides service to local phone companies. The company has a number of points of presence (POPs) conveniently located near the networks it serves. The local phone companies provide service to enterprise customers via primary rate interfaces (PRIs) to private branch exchanges (PBXs). Figure 4: Company B provides service to local phone companies.10 | SSR Application HandbookWith deregulation, Company B decides to enter the local service market and ofer fixed-line services directly to enterprise customers. Company B can deliver substantial savings by cutting out the middle men, the local phone companies. With SIP trunking, Company B can enable business customers with IP PBXs to use their Internet connection to provide of-net service. In addition to voice services, Company B wants to create a foundation for delivering multimedia services to its enterprise customers in the future. Company B faces several challenges and needs a solution that will enable the company to: |.cv|Jo orto.p.|so vc|co so.v|co |nnoJ|.to|v .|||o laying the foundation for future multimedia SIP services. V.|rt.|r |c. st..tJp ccst .|t|cJt ccnp.cn|s|rc the long-term plan.The company could implement a softswitch-based solution, but that alternative has a number of disadvantages. Since it is based on a per connection cost model, the approach can become costly very quickly. The softswitch-based model is voice centric and may not be suited to delivering multimedia services. Softswitch implementations usually are deployed with the switch vendors choice of application server, so it is difficult to gain the economy of a best-of-breed solution.www.tekelec.com | 11Figure 5: SIP trunking enables enterprise customers to use their Internet connection for of-net services.Company BPOP POP POPLocal Network 2Local Network 3Local Network 4Local Network 1POPIP PBXIP PBXSIP Trunking directly from Enterprise to Company B12 | SSR Application Handbooksolution:By implementing Tekelecs SSR solution, Company B can use a session-based approach, which balances cost and fexibility. The SSR creates a SIP signaling and session control layer that routes on-net calls (IP PBX to IP PBX) over the VoIP network, of-net local calls (IP PBX to local numbers), and of-net long-distance calls (IP PBX to long-distance numbers). A public switched telephone network (PSTN) gateway handles IP PBX to PSTN calls. In the process, the company also creates a framework that is based on Internet Engineering Task Force (IETF) and 3GPP standards for the delivery of multimedia services. The solution enables Company B to create a volume-based cost structure and reduces costs by allowing the company to select best-of-breed application servers.www.tekelec.com | 13Figure 6: SSR creates a SIP signaling and session layer to route on- and of-net calls.Benefits:With the SSR solution, Company B can compete with local telephone companies by ofering SIP trunking to enterprise customers. The company receives additional benefits that include: |.v|rc t|o |cJrJ.t|cr |c. nJ|t|noJ|. so.v|cos S.v|rc ncrov bv n.x|n|.|rc t|o c.p.c|tv c| application servers through load sharing and fexible subscriber management. .o.t|rc . S|| poo.|rc pc|rt tc |rto.ccrroct with other VoIP providers. POP POPLocal Network 2Local Network 3Local Network 4Local Network 1POPIP PBXIP PBXEasily add best-of-breedSIP AS for new servicesSIP ASPOPPSTNGWSIP Signaling Router14 | SSR Application HandbookUse Case 3: SIP NumBER PORTABILITyProblem: Company C, a long distance operator, entered the local calling service market by deploying Tekelecs SSR solution to build a SIP trunking infrastructure. Company C is an operator in the call routing sequence immediately prior to the terminating operator. So, its customary for Company C to perform number portability, or NP service, for VoIP calls from their SIP trunking service. The company could simply dump calls onto the PSTN gateway and use its existing time division multiplexing (TDM)-based, number portability solution to route calls to the correct network. However, to do so, there must be adequate intelligent network capacity to handle the increased traffic, and the terminating network must be TDM. If the terminating number is an IP PBX or belongs to another VoIP provider, the call must be shuttled from VoIP to TDM and back to VoIP again. Running pure VoIP calls over the TDM network to perform NP wastes capacity on the PSTN gateway and degrades voice quality.www.tekelec.com | 15Figure 7: Calls destined for a VoIP provider or IP PBX must be routed over the TDm network.POP POPVoIPOperatorLocal Network 2Local Network 3Local Network 4Local Network 1POPIP PBXIP PBX919-460-5500 POP919-460-5500NPDBPorted in from NW2PSTNGWSIP Signaling Router16 | SSR Application Handbooksolution:Company C could replicate an NP solution in its SIP domain, but that is an expensive approach. A more cost-efective and efficient method is to make the TDM-NP solution available to the SIP network. The TDM-NP database can be accessed using the SSRs SS7 access feature. This capability allows the SSR to augment its routing capabilities with data from the SS7 domain. The SSR provides NP services to the SIP domain in one of three ways: |Jnbo. pc.t.b|||tv cc..octoJ |c....J|rc p.cxv |o SSR receives a request from an originating user agent (UA) such as an IP PBX. The SSR performs the NP function and then forwards the request to the appropriate SIP endpoint for call completion. |Jnbo. pc.t.b|||tv cc..octoJ .oJ|.oct so.vo. |o originating UA sends a request to the SSR, which performs the NP function to determine the end- point destination. The SSR then sends a SIP redirect message to the UA that instructs the UA to forward the request to the appropriate destination. |Jnbo. pc.t.b|||tv cc..octoJ |c....J|rc .pp||c.t|cr server: After receiving a request from the originating UA, the SSR performs the NP processing to locate the called number. It modifies the request with the destination information and sends it back to the originating UA. The UA then proxies the call to the appropriate SIP endpoint.www.tekelec.com | 17Benefits: S|rco || |s Jop|cvoJ t|.cJc| . st.rJ..J S|| framework, the approach can be used in the next-gen network as well as a future IMS network. |rJtcorJ noJ|. t..rsp..orcv |s n.|rt.|roJ. sc the NP solution can be applied to voice service AND any other type of multimedia service such as a video or IPTV. |o SS.ccoss |o.tJ.o JsoJ |c. t|o || .pp||c.t|cr .|sc supports access to other SS7-based applications like toll-free and message-waiting indicator as well as HLR mobility information for wireless operators.Figure 8: SSR accesses TDm-NP database using SS7 access feature.SIP DomainTDM DomainSIPDeviceTDMDeviceSIPDeviceNPDBSIP SIPAIN/INAPMedia TransparencyAIN/INAPSIP Signaling Router18 | SSR Application HandbookUse Case 4: CENTRALIzED SIP ROuTINgProblem:Company D, a Southeast Asia hub provider, ofers voice transit and signaling services to fixed-line and mobile operators. The company deployed softswitch technology to take advantage of lower IP transport costs. Softswitches, which serve as POPs, are installed throughout Southeast Asia in a fully meshed framework. Every switch must be defined in the translation table of every other switch.Figure 9: Softswitches, serving as POPs, form a fully meshed architecture.TDM ClientTDM ClientTDM ClientTDM ClientTDM ClientTDM ClientTDM ClientTDM Client SIP ClientCompany D NetworkTDM ClientSSPOPSSPOPSSPOPSSPOPSSPOPSSPOP SSPOPSSPOPPOPVoiceTextMultimediawww.tekelec.com | 19Company D would like to expand its network to serve other Asian markets. The company also plans to enhance its portfolio by ofering transit services for text messaging and multimedia applications. And, it would like to provide SIP peering as an alternative to TDM to other VoIP providers.The new business plan presents a number of issues for the meshed, softswitch network. Expanding the network requires the addition of new softswitches to increase capacity. Provisioning is complex as each new piece of equipment must be provisioned with the routing entries for all of the existing softswitches. And, the existing softswitches must be updated with the routing entries for the new equipment. Since routing is based on pre-defined SIP trunks, route management becomes increasingly complex as the network expands. Service and subscriber data are tightly coupled with the softswitch, making it difficult to change an existing service or add new applications uniformly.Company D must address several complex issues related to growing its network, including how to: |xp.rJ |ts rot.c.k /|| koop rot.c.k cpo..t|cr costs low. O|o. vc|co .rJ rcrvc|co so.v|cos /|| .oJJco capital costs. |.ovort Joc..J.t|cr .s noJ|. |c.s t|.cJc| its network.Like many operators, Company D views these as three, unrelated challenges. As a result, they deploy multiple, point solutions, which increase long-term CAPEX and OPEX. However, if Company D took a holistic view of the network, they would see that they are, in fact, all related. A piecemeal approach will not address the challenges because solving one problem likely worsens another. 20 | SSR Application Handbooksolution:Company D creates a SIP-based reference architecture over its existing network by deploying the SSR as a SIP proxy. With this approach, all calls are routed by default from the softswitch to the SSR. The SSR makes layer-5 SIP routing decisions based on advanced routing algorithms and forwards the request to the appropriate SIP destination.Benefits:The company now has a centralized SIP signaling and session control framework that: /cts .s . .cJto n.r.co. |c. .|| c| t|o sc|ts.|tc|os. relieving them of routing functions. |||n|r.tos t|o nos| rot.c.k. sc t|o.o |s rc |crco. a need to provision translation tables on each and every switch. V.|rt.|rs orJtcorJ noJ|. t..rsp..orcv sc t|o endpoints can communicate using any media voice, text, video, or data streaming. |.oso.vos noJ|. oJ.||tv boc.Jso t|o.o |s rc decoding/encoding required in the network. |.cv|Jos . cort..||.oJ S|| ncr|tc.|rc pc|rtwww.tekelec.com | 21Figure 10: SSR creates a SIP-based reference architecture.Company D NetworkTDM ClientTDM ClientTDM ClientTDM ClientTDM ClientTDM ClientTDM ClientTDM ClientSIP ClientTDM ClientSIP ClientSSPOPSSPOPSSPOPSSPOPSSPOPSIP Signaling RouterSIP Signaling RouterPOPSSPOPSSPOPSSPOPPOP22 | SSR Application HandbookUse Case 5: SPECIALIzED SIP PROXyProblem:Company E is a provider of fixed and mobile services. The company maintains its operation as two, separate businesses Company E Telecom and Company E Mobile. The fixed and mobile networks are loosely coupled through TDM peering. Each network views the other as a foreign network. Figure 11: Company Es network before consolidation.HLRMSC SMSCSCPSwitchSoftswitchCompany E MobileCompany E Telecomwww.tekelec.com | 23Company E wants to consolidate the networks and create a single operating entity Company E to reduce its operating costs. The company also plans to expand its oferings with integrated mobile and fixed services, mobility solutions for fixed-line enterprise customers and future multimedia services.Since Company E already has some SIP deployments in its fixed-line network, it has decided to take the opportunity to upgrade its underlying wireless network technology to SIP as well. By doing so, the company can lower the cost of network integration and create a future path for multimedia services. Company Es plan is to cap its existing TDM-based mobile switching centers (MSCs) and begin deploying SIP-capable mobile softswitches. Its strategy is to interconnect the mobile softswitches with the existing wireline SIP softswitches.Figure 12: Company E connects mobile and wireline softswitches with SIP technology. Company E24 | SSR Application HandbookHowever, Company E faces a problem common to many operators: diferent vendors supply the mobile and landline softswitches. The softswitches are unable to establish sessions because the vendors use diferent SIP implementations. The two vendors refuse to recognize the interoperability issue as a problem, but they gladly will provide a customized solution to Company E if the company is willing to pay for it.Company E is caught in a situation called vendor lock-in. As long as the company deploys equipment from a single vendor, there is no problem. But, when it introduces equipment from another vendor, interoperability problems arise. This situation creates significant challenges for the company. |c. c.r |t sc|vo t|o |rto.cpo..b|||tv |ssJo .|t|cJt spending an excessive amount of money for a customized solution or being forced to purchase all of its equipment from a single vendor? |c. c.r t|o ccnp.rv .vc|J t|o s.no p.cb|on in the future as it brings new elements from other vendors into the network?solution:Company E deploys the Tekelec SSR as a protocol mediation point between the diferent vendor products. This approach creates an architectural solution that is independent of the endpoints and eliminates interoperability problems. The SSR solution, which is deployed in the signaling layer, can be implemented in one of two ways: directly on the SSR, or by having the SSR proxy to an external application which provides the protocol mediation.With the SSR solution, Company E creates a SIP-based, NGN reference architecture over its existing network. In this role, the SSR acts as a proxy server to route SIP traffic between the mobile and landline softswitches. It also forms a mediation point that fixes protocol variations on the fy between the softswitches.www.tekelec.com | 25Benefits:Company E now has the SIP signaling and session control framework that solves its immediate interoperability needs and: .o.tos t|o |cJrJ.t|cr |c. . nJ|t|vorJc. environment and future multimedia services. |r.b|os t|o ccnp.rv tc c|ccso bostc|b.ooJ products, avoiding vendor lock-in. |.cv|Jos . cort..||.oJ S|| ncr|tc.|rc pc|rtFigure 13: SSR acts as a mediation point between softswitches and routes traffic between them.Modify ModifySIP Signaling RouterEndpoint Equipmentfrom Vendor 2Not My FaultEndpoint Equipmentfrom Vendor 1Not My Fault26 | SSR Application HandbooksummaryThe current NGN architecture has no core signaling and session framework, which greatly limits its expansion capabilities. History shows that the signaling and session control layer is critically important to any large-scale network architecture. Having softswitches and other endpoints perform layer-5 session management may be sufficient for fairly small deployments and simple management tasks. But, as the network expands, the lack of a capable session framework introduces a host of network issues. A suitable session framework that ofoads the various signaling and session tasks from the edge NGN elements enables NGN networks to expand efficiently and avoids the pitfalls created by a point- to-point, virtual-mesh routing network. Just as core routers are used to minimize the routing burden on IP endpoints, layer-5 SIP routing capability can be used to reduce the routing burden on NGN endpoints by centralizing session management tasks at the network core instead of at each endpoint. The resulting architecture can expand systematically to support VoIP subscriber growth, deliver advanced multimedia services and create the foundation for future technologies and services.www.tekelec.com | 27about TekelecTekelec, a global leader in core multimedia session control, mobile messaging and network intelligence, ensures scalable, secure and highly available communications. The companys market-leading signaling solutions enable the interworking of diferent network applications, technologies and protocols, providing a smooth transition to next-generation networks. Tekelec has more than 20 ofces around the world serving customers in more than 100 countries, with corporate headquarters located near Research Triangle Park in Morrisville, N.C., U.S.A. For more information, please visit www.tekelec.com. Appendix-1: Acronyms used in this document3GPP 3rd Generation Partnership ProgramAS Application serverHLR Home location registerIETF Internet engineering task forceIMS Internet protocol multimedia subsystemIP Internet protocolIP PBX Internet protocol private branch exchangeLD Long distanceMSC Mobile switching centerNGN Next generation networkNP Number portabilityPOP Point of presencePRI Primary rate interfaceSCP Service control pointSIP Session initiation protocolSMSC Short message service centerSS7 Signaling session 7SSR SIP signaling routerTDM Time division multiplexingUA User agentVM Voice messagingVoIP Voice over Internet protocolCorporate inquiries: Tekelec 5200 Paramount Parkway Morrisville, North Carolina 27560 (USA) Phone: 888.628.5521 Phone: +1.919.460.5500 FAX: +1.919.460.0877Europe, middle East and Africa inquiries: Tekelec Katherine House 85 The High Street Egham, Surrey TW20 9HFUnited Kingdom Phone: +44.1784.437000 FAX: +44.1784.477121Asia-Pacific inquiries: Tekelec Singapore Pte Ltd 15 Hoe Chiang Road #06-06 Tower 15Singapore 089316 Phone: +65.6796.2288 FAX: +65.6796.2299Caribbean and Latin America inquiries: Tekelec Caribbean & Latin America (CALA) 5200 Paramount Parkway Morrisville, North Carolina 27560 (USA) Phone: +1.919.460.5500 FAX: +1.919.460.0877All sales related inquiries contact: sales@tekelec.com www.tekelec.com 2009 Tekelec. All rights reserved. Printed in U.S.A. TKLC-HB-001.1-NA-10-2009