At Your Service
December 2001

Jonathan Rosenberg SIP Origination And Termination

BY JONATHAN ROSENBERG


Carriers offering VoIP services are beginning to see a sharp increase in opportunities for revenue through Session Initiation Protocol (SIP)-based wholesale origination and termination service. The service employs an IP peering interface to allow its customers (who are retail service providers) to either send traffic to the origination and termination service provider for termination to the PSTN, or to receive traffic originating from the PSTN. In either case, SIP is used as a standard for call control. There are several industry and technology trends that are contributing to the attractiveness and feasibility of deploying a network to offer origination and termination service (OATS). The attractiveness of deploying origination and termination depends entirely on the existence of retail providers that can make use of the service. While there has been a continually growing pool of such providers, the pool has just become an ocean with the entrance of Microsoft as a retail provider of VoIP services.

Microsoft has embraced SIP to allow its communications applications and service initiatives to interwork with ITSPs for PSTN termination. By outsourcing PSTN termination, Microsoft is able to focus on what it does best: enhancing the end-user experience and developing endpoint technology and features. The details of managing gateways and performing call routing are not important for them to own, so outsourcing is a natural direction. In turn, the opportunity for the termination provider is very large, as Microsoft is able to leverage its installed OS customer base and bring VoIP services under the .NET umbrella. The adoption rate and market size of PC-phone service is therefore greater than if either Microsoft or the provider attempted to unilaterally build all of the vertical components required to deliver this service.

Utilizing an origination and termination service can help eliminate what was once a prerequisite to economically providing VoIP-based services to end users: a complete worldwide gateway network buildout. Service providers can preserve capital investment and maintain focus on subscriber acquisition and service development by utilizing an origination and termination provider for PSTN interconnection. This lowers the barrier to entry for new service providers, and can lower operational costs for existing PSTN-based service providers (such as unified messaging providers and voice portals). These existing providers can simply cease paying the high costs of PSTN interconnect and switch to the lower cost IP-based origination and termination service. This only requires that they add an SIP interface to their existing gear, as opposed to buying an entire gateway network. It is clear that Microsoft has recognized the value of focusing on subscriber acquisition, subscriber ownership, and the overall subscriber experience, while outsourcing the execution of an application itself. Indeed, this is the very heart of the .NET initiative.

MICROSOFT IS NOT ALONE
Other retail service providers are moving to exploit the opportunity presented by origination and termination providers — lowering the barriers to entry for VoIP-based services, enabling the expansion of services to a larger subscriber base, expansion of service to wider geographic areas, and allowing access to the rich service platforms available on IP networks. Some areas these service providers are focusing on include enterprise IP services, residential second line, call centers, voice portals, conferencing, and others.

The existence of origination and termination service networks is not the only trend that is helping to create growth in the retail VoIP provider market. Several technology trends are making it easier than ever to develop new, revenue-generating applications more easily and rapidly than ever before. One trend is the integration of Web, instant messaging, presence, and e-mail with VoIP. Many traditional telecommunications applications are easily enhanced by adding these other components. For example, using instant messaging to deliver notifications of people joining and leaving a conference is a simple yet valuable enhancement to conferencing applications. Using a buddy list to track voice mail messages provides a way to enhance unified messaging applications. Another trend is the growth in the availability and maturity of application development platforms that can deliver these integrated applications. These platforms have been built to mirror the Web-based development models, bringing to bear a large developer community that can quickly come up to speed on building communications applications.

This is all good news for a provider building out an origination and termination service network — trends are indicating that there will be customers for such networks (such as Microsoft). Fortunately, it is easier than ever to build out an origination and termination service network. In the past, VoIP providers were burdened with the task of integrating equipment from several providers for a complete solution. However, with the maturation of the industry, vendors have begun to partner in order to complete this integration ahead of time, so that providers can purchase a solution that is already tested in the lab. This is a substantial benefit to the provider, since it is not an easy integration problem. Traditionally, these networks are built using several distinct components: firewalls, SIP proxies, billing mediation servers, gateways, and softswitches, each of which is frequently built by a different vendor. These components address the four key requirements to build an OATS network:

  1. Security — the interface between the origination and termination service network and the customer must protect the facilities from unauthorized usage and denial of service attacks. It must also ensure that only SIP messages from authorized customers are routed within the origination and termination service network.
  2. Accounting — the wholesale-retail business relationship between the provider and the customer requires a method for tracking each customer’s resource utilization based on aggregate minutes, and specific PSTN termination or origination points, to allow service billing.
  3. Routing — to originate calls to VoIP endpoints, routing must be able to match a telephone number to a specific customer. To terminate calls, routing must match a telephone number to an egress PSTN PoP using routing tables that enable least-cost route selection. At the network level, routing must also serve to provide a level of network scalability, redundancy, and reliability, to allow routing around a failed or busy node, and high levels of aggregate performance.
  4. Linear scalability at each functional plane — the network must be scalable at each of the above three functional layers, so that network investment more closely tracks growth in peering interfaces or overall capacity.

“FUTURE PROOF” NETWORKS
Fortunately, these elements, and the four basic capabilities they provide, are needed not just for origination and termination, but for a variety of totally new wholesale service opportunities. No matter what application is being offered, security, accounting, routing, and linear scalability are all key components. This means that a provider can build out an origination and termination network to support basic origination and termination solutions. Breaking into a totally new market, such as hosted applications, is only an incremental addition to their existing network. This means that an origination and termination network is future proof — it can support today’s origination and termination needs, and also tomorrow’s application needs. While building “future-proof” networks has always been a primary goal of service providers, today’s cautious economic environment has made achieving this goal even more significant.

Consider Microsoft termination. Initially, an origination and termination service provider builds a network to support PC-to-phone calls from the Windows Messenger client. As time goes on, they realize that there is a good market opportunity for adding conferencing capabilities. A Messenger user can get a personal conference bridge number, and when they dial this number from their Windows client, they are connected to an IP-based conference associated with that number. To add this capability, the origination and termination service provider needs to add an IP conferencing platform and SIP application server, but they can completely reuse their proxies, billing mediation servers, softswitches, and gateways. The result is an incremental cost for a substantially new capability. The addition of the next application, unified messaging, for example, might require only the addition of new application software on the SIP application server, as the other components in the origination and termination network are reused for the rest of the application. The result is an even smaller incremental cost for another substantial market opportunity.

In summary, origination and termination service is looking more attractive than ever, thanks to the entrance of Microsoft as a potential customer of such networks, the increasing opportunities for other service providers to utilize and termination networks, the decreasing costs of deploying origination and termination networks, and the increasing opportunities for future revenue with minimal cost.

Jonathan Rosenberg is chief scientist at dynamicsoft, Inc. For more information, please visit the company’s Web site www.dynamicsoft.com.

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