Operating in Two Worlds: Routing Plan Management for VoIP/PSTN Compatibility Nominum, Inc. 2385 Bay Road Redwood City, CA 94063 (650) 381-6000 www.nominum.com
Contents Operating in Two Worlds... 1 Routing Plan Management in a Converging World... 1 Routing plans for VoIP calls... 2 Legacy VoIP? Already?... 2 The Role of IP-application Routing Directories... 3 ENUM is the foundation for VoIP peering... 3 Routing Plan Management in IP-application Routing Directories (IPRDs)... 4 Requirements for Routing Plan Management with the IPRD... 4 Support for SIP for switch integration... 4 Cascading queries that tap the entire VoIP peering ecosystem... 4 Advanced routing logic... 5 Carrier-grade performance, manageability, reliability... 5 Nominum Navitas... 6 Summary... 6 About Nominum... 8 2007 Nominum, Inc. All rights reserved. Nominum is a registered trademark.
Operating in Two Worlds Convergence may be happening, but it isn t easy. As large carriers enable VoIP on their networks, they face difficult business and technical decisions. Carriers need to figure out how to operate in both PSTN/TDM and VoIP worlds, profitably and efficiently. Telcos trying to manage a viable business that has evolved over decades face extreme challenges, including: Supporting and adopting VoIP without cannibalizing their existing telephony business model. Managing dual networks (PSTN and IP), with sufficient capacity on each. Sustaining current business models and relationships while operating in this dual mode. The problems of compatibility between PSTN and IP telephony go beyond technical issues of switching they affect the core business models of major carriers. Specifically, how do you manage the routing plans and tariffs established in the PSTN world when supporting both types of telephony? What happens to termination settlements for VoIP-terminated calls? How do you handle the new ecosystems of small VoIP carriers to whom you may need to route calls? Are all VoIP calls free? VoIP complicates the call routing plans and call termination settlements that are essential to carrier profitability. Telcos are both suppliers of call termination to other carriers and customers of other carriers for call termination, and VoIP potentially changes the basis of these relationships. Carriers looking to sustain their business models must determine how to manage and aggregate routing plans and financial agreements in a converging TDM and VoIP environment. Routing Plan Management in a Converging World Carriers dedicate many resources to analyzing margins on call termination for PSTN calls, which may require routing through multiple intermediate providers. Carriers deploy Least Cost Routing systems and technology to determine the optimal routes based on bandwidth, cost and quality. They also negotiate settlements for these routes, which help determine profitability in a very direct sense. Even before the advent of VoIP, this model was becoming more complex to manage as mobility and Number Portability in fixed and mobile networks complicated numbering plans. The geographic and hierarchical distinctions in the E.164 phone number no longer map directly to carriers, as subscribers can take their numbers with them between carriers. Furthermore, importing number portability data across international boundaries was not even considered by carriers in the old paradigm due to limitations in handling large volumes of numbering data in legacy networking elements. The SS7 has a rich layer of intelligence built into it in databases, such as SCPs and number portability databases, as well as routing logic from carriers Least Cost Routing technologies. This intelligence is missing from the IP networks that service VoIP 2007 Nominum, Inc. All rights reserved. Nominum is a registered trademark. 1
telephony. Routing plan management is essential to carrier profitability how does it translate to the IP world, using a so-called dumb network of layered protocols? Routing plans for VoIP calls VoIP initially gained popularity as a means of bypassing long distance or international carriers by terminating calls over IP networks. Carriers, not surprisingly, don t want to eliminate existing revenue streams. They want settlement to terminate VoIP as well as TDM calls. And carriers have rich networks of peering or interconnection agreements that support their current business models. And while the free appeal may have helped fuel the initial uptake of VoIP among early adopters, it may have delayed broader and business VoIP by restraining the necessary investment to provide robust, high quality and highly reliable voice service. Much of a carrier s business model is implemented in its routing plans, which cannot be discarded as VoIP support joins TDM-based telephony. These routing plans must help bridge the change to IP. For example, VoIP has removed barriers to entry for a new class of carriers. A growing number of small VoIP providers offer VoIP service to SMBs often to relatively small customer bases ranging from 2,000 to 50,000 subscribers. While market consolidation may yet occur in the near future, today both large and mid-sized carriers need to offer VoIP termination services to these small providers. And, larger carriers need to implement VoIP peering among each other to eliminate the need to route VoIP-to-VoIP calls over the PSTN. When carriers can terminate VoIP calls directly over IP networks to the termination provider, without using the PSTN or intermediate carriers, they lower the costs on those calls. Doing so requires peering agreements that offer visibility into whether the destination number is VoIP-enabled. As an example, International exchange Carriers started shifting their core networking infrastructure to IP while maintaining traditional telephony termination (i.e., routing) agreements. Even with these agreements in place, there are many possible routes to connect VoIP calls. And when calls originate on VoIP but terminate in the PSTN, or vice versa, routing possibilities are even more complex. Carriers can use far-end hop-off or least-cost routing for the PSTN part of a PSTN-VoIP call. Again, managing the margins through careful call routing is essential. Legacy VoIP? Already? To complicate the situation even further, VoIP itself is still in transition, with changes in technology as well as the evolution of IMS. Early providers of VoIP (upstarts in the broader telecommunications timeline) are now the legacy VoIP providers. Older softswitch infrastructures that have not kept up with the latest SIP standards or architectures are referred to as legacy VoIP. And traditional telephony vendors migrating to VoIP today are adopting the second generation of VoIP. Nothing, it seems, is standing still in this market carriers have to look for long-term solutions that will be capable of withstanding the constantly-changing technology underpinnings. This is a strong argument for deploying standards-based approaches to 2007 Nominum, Inc. All rights reserved. Nominum is a registered trademark. 2
routing plan management, distinct from individual softswitch capabilities. Solutions that are tied closely to specific switches or hardware vendors limit flexibility and agility as technology and business needs change. The Role of IP-application Routing Directories What carriers need is a way to aggregate and manage routing plans across both TDM, socalled legacy VoIP and emerging VoIP. This will require decoupling the routing plan management from the softswitch infrastructure, and avoiding the hassle of manual management of electronic spreadsheets that move from someone s desktop all the way to the configuration of a switch. By doing so, carriers can sustain their business of managing and delivering telephony traffic, regardless of the transport used. A standards-based approach offers the best longevity in a rapidly-changing VoIP environment. And the best candidate, from a standards perspective, to fill this role is the technology already chosen to implement VoIP peering in an E.164-dominant world: ENUM. ENUM is the foundation for VoIP peering At its core, the ENUM protocol maps E.164 phone numbers to accessible IP addresses of switching equipment. ENUM was initially envisioned and defined by the IETF to enable a global, public directory of phone numbers. Today, however, it has become an enabler of carrier or private VoIP peering implementations among carriers. ENUM directories enable end-to-end IP connectivity for VoIP calls, if carriers have established peering relationships for VoIP call termination. An ENUM-based directory returns a Uniform Resource Identifier (e.g., sip:john.doe@nominum.com) for when queried with a phone number the URI is used to retrieve an actual IP address for the source. There are several important factors to note about ENUM: 1. ENUM uses the Domain Name System (DNS) at its core the highly scalable, global directory, mapping domain names to IP addresses. However, telephony requirements far exceed the capabilities of most DNS servers. A telephony-grade ENUM-based directory needs flexible provisioning and highly scalable performance for a high load of concurrent queries and updates. 2. ENUM goes beyond VoIP Peering its potential applications in converging networks are much broader. ENUM records are highly flexible and extensible, and can connect all kinds of multimedia services and applications to a phone number, including routing information. As an open IP-based technology standard capable of connecting routing information to telephone numbers, ENUM is at the core of a new network entity that serves the broader function of routing traffic between IP networks: the IP-application Routing Directory (IPRD). 2007 Nominum, Inc. All rights reserved. Nominum is a registered trademark. 3
Routing Plan Management in IP-application Routing Directories (IPRDs) The IP-application Routing Directory, using ENUM technology at its core, is a way to embed the intelligence of SS7 networks e.g., LNP databases, routing plans driven by external Least-Cost Routing systems in IP networks. An IPRD is a directory that delivers routing information for phone numbers, within an IP network. In the converging VoIP ecosystem, it acts as the IP equivalent of an SS7 SCP. It is a central point of reference for mapping telephone numbers on IP, as well as country code routes, prefixes and extended prefixes, thereby eliminating the proliferation of disparate routing tables requiring manual management. As a resident directory in the IP network, the IPRD is not dependent on legacy switches and softswitches. Decoupling the routing plan management from the switch offers the flexibility to handle changing technology and data sources alike. Requirements for Routing Plan Management with the IPRD Implementing routing plan management with an IPRD in IP networks is a relatively new approach to achieving compatibility between TDM and VoIP telephony. Although the IPRD in this role leverages open standards (ENUM and SIP), its role imposes requirements that are unique to the converging telephony network. This section discusses some of the attributes necessary to effectively aggregate and implement routing plan management in an IPRD. Support for SIP for switch integration To integrate with multiple softswitches and support constantly-changing technologies, the IPRD must adhere to widely-accepted industry standards. In the case of the IPRD, the two most relevant are ENUM and SIP. We have already discussed ENUM, which enables E.164-based routing within IP networks. SIP is today the most widely deployed VoIP protocol in many parts of the world, and SIP support is integrated in many VoIP switches ( legacy and current). The IPRD, by supporting the SIP protocol, essentially creates a SIP-to-ENUM interface that enables multiple softswitches to integrate with the IPRD using SIP redirect processing. This means that the switch only needs to support SIP not ENUM directly to leverage the benefits of consolidated routing plans in the IPRD. In this way, the IPRD empowers a variety of switches to handle any number translation/redirection service, including LNP, private dialing plans, toll-free and service code translation. Cascading queries that tap the entire VoIP peering ecosystem As mentioned already, the VoIP environment is under constant change. An entire VoIP ecosystem is emerging with aggregators expanding peering points for large and small carriers alike. 2007 Nominum, Inc. All rights reserved. Nominum is a registered trademark. 4
This means that the sources of VoIP numbering data themselves are fluid and changing. An IPRD must be able to handle provisioning from multiple sources, as well as the ability to query multiple sources, including internal or replicated registries, external aggregators, with public and private data. For example, a carrier might manage a number of private, bilateral peering agreements, which are implemented in an internal ENUM-based directory. In addition, they may access registries from aggregators managing multilateral peering arrangements. The IPRD should support the retrieval of data from these multiple sources through concurrent parallel queries. Advanced routing logic The IPRD needs to support many different routing plans. As you consolidate and aggregate routing plans in a single source, the IPRD must be able to provide multiple choices for a route. This requires more sophisticated capabilities than are available in the native DNS on which ENUM is based. When a call request is made, there are many parameters provided that may be useful in route selection including called party, calling party, where the request came from, who made the request, and the request s session parameters. Even in a pure ENUM world, the operator may choose to look at specific information in the request, apply logic based on the information, and make a more intelligent decision on how that session should be handled. The IPRD must have the ability to inspect the available session parameters whether it is ENUM, SIP, or an alternate protocol apply logic to them, and return the most appropriate treatment for the request. The IPRD must also be capable of offering the flexibility to perform this function in a multi-vendor switching environment where the endpoint capabilities differ significantly. For example, an operator may set up multiple routes for the UK country code (+44), with additional routes for London (+44.20 city code 020, the left-most zero for local dialing). Depending on the configured parameters for those two routes, a call to a number in London can generate different results depending on the calling party. Parameters can be adjusted to return an exhaustive set of results or the most specific set that best matches the combined calling-called party route in order to give the carrier the flexibility to implement the real-time routing logic. Furthermore, the IPRD must have the ability to understand variations in dial plans within a country. Many countries do not follow a strict numbering hierarchy, which can pose challenges in a pure ENUM environment. The IPRD must also integrate with external Least Cost Routing (LCR) engines, to support complex LCR routing information and make it available in real time to the switching infrastructure. Without the ability to consolidate and integrate with LCR engines and softswitches, operators must manually manage and update the switching infrastructure, introducing the possibility of errors, as well as delays in activation. Carrier-grade performance, manageability, reliability Because the IPRD participates in the call-setup process, it needs highly scalable and lowlatency performance. For most carriers, this will require a scalable and distributed 2007 Nominum, Inc. All rights reserved. Nominum is a registered trademark. 5
architecture, with redundant components protecting against failures and providing load balancing capabilities. Integration with an element management system is essential, as are highly resilient operations and robust management interfaces to ensure a complete view of the network state and the ability to quickly react when issues are encountered. Nominum Navitas Nominum Navitas is a complete IP-application Routing Directory for next-generation networks. Designed to integrate easily in carrier networks, Navitas delivers ENUM-based services for VoIP peering, in-network LNP data replication, MMS exchanges, IP Multimedia Subsystem (IMS) networks, and intra/inter-carrier application-level routing on IP networks. Navitas can integrate massive amounts of subscriber and routing data from multiple sources, including provisioning systems, peering partners and service bureaus. It offers very fast responses to queries, even while information undergoes real-time updates. The product implements patent-pending high-density compression for ENUM and routing data, and provides innovative zoning techniques for simplified data partitioning and query logic simplicity. Nominum has worked closely with carriers worldwide to extend and enhance the role of the IPRD in next-generation networks. As a result of this work, Nominum has enhanced Navitas with several features targeted at the needs of carriers trying to manage compatibility between TDM and VoIP services. These include: Enhanced prefix routing Advanced routing logic SIP support for better interoperability Cascading queries to multiple sources in the peering ecosystem Enhanced statistics collection, reporting, and management capabilities Summary Routing plans are essential to carrier business models, and must be managed and sustained in the converging telecommunications environment that supports both TDM and VoIP traffic. Carriers need the flexibility to establish and manage the relationships, settlements and routing plans that sustain their business. The IP-application Routing Directory, leveraging a highly scalable, ENUM-based directory structure, can fill this role in converging, next-generation network environments. An IPRD designed and enhanced for the routing plan management function can decouple routing plans from specific switches and support complex and dynamic routing logic. Nominum works with carriers worldwide to meet their IP routing/naming/addressing needs. Nominum Navitas is an IPRD designed specifically to meet carrier requirements 2007 Nominum, Inc. All rights reserved. Nominum is a registered trademark. 6
with telephony-grade performance in the IP network environment. By consolidating and aggregating routing plan management in IP networks, carriers can ready themselves for the continued transition to IP without sacrificing the business models that have sustained them thus far. 2007 Nominum, Inc. All rights reserved. Nominum is a registered trademark. 7
About Nominum Nominum's network naming and addressing solutions power the world's largest alwayson networks. Nominum is a global provider of ENUM-based IP-application routing directories, DNS, and DHCP solutions that enable communication providers to deliver high quality always-on broadband internet and innovative services to their customers, including VoIP, push to talk, fixed-mobile convergence, IPTV, and triple-play. For further information, visit www.nominum.com. 2007 Nominum, Inc. All rights reserved. Nominum is a registered trademark. 8