Internet multimedia subsystem (IMS), the open standardized architecture that defines how Internet protocol (IP) networks should handle voice calls and data sessions, is already established as a wireless standard. Its adoption by the European Telecommunications Standards Institute (ETSI) (and extension into Telecoms and Internet Converged Services and Protocols for Advanced Networks [TISPAN]) and CableLabs (and extension into PacketCable multimedia) means that it is also poised to become an important component of these other standards.

Consumer demand for rich, real-time communications experiences is spurring whirlwind innovation-in new devices, applications, and value-added services. And this dynamic is itself fueling further consumer demand, creating a new competitive environment and driving the requirement to get new services to market more quickly than ever before. In this climate, operators know that to achieve high performance, they must rapidly transform themselves into agile services businesses-and IMS has much to offer them, particularly in terms of cost reduction.

By providing control over IP and giving operators the power to deliver innovative multimedia and voice services over 3G, next-generation and legacy networks, IMS carries clear and substantial business benefits. For wireless operators, it will help them to achieve high performance by enabling innovative, personalized, and context-aware customer experiences through multimedia content delivery. For wireline operators, under mounting pressure from mobile operators and VoIP providers, it has the potential to reduce operational costs, enhance service offerings, and speed reaction to market demands, significantly improving customer retention. And for the incumbent operators that already run wireless, wireline, and cable networks, IMS will be the catalyst for true fixed-mobile convergence (FMC), enabling them to extend the reach of carrier-class service delivery over their ubiquitous and access-agnostic IP infrastructures. It will also provide major revenue opportunities by giving operators the potential to offer (and charge for) applications that are hosted and developed by third parties.

IMS provides operators with a standardized next-generation network (NGN) architecture. Running over standard IP, IMS is the "common element" that will allow fixed and mobile subscribers to roam seamlessly between fixed and mobile networks, interacting via applications such as VoIP, video/picture sharing, instant messaging, and P2P gaming. As the "intelligence on top of IP," IMS ensures that multimedia sessions between IMS users, between IMS and Internet users, and between Internet users are all established with the same protocols. Interfaces with service developers are based on the same protocols, meaning that service providers can assertively position themselves in the value chain for delivery. By merging the Internet, wireline, and wireless worlds, it will ensure that users can have anytime/anywhere access to compelling new services, as well as give service providers a robust foundation for value creation.

IMS cannot, on its own, help companies to achieve high performance through FMC. What is needed is a concept that will enable operators to exploit maximum benefit from this technology while ensuring that it does not become siloed.

The IMS imperative is proving to be a powerful catalyst for change—driving market activity among vendors, as well as FMC strategies among operators.

However, although operators worldwide have announced IMS trials, there has yet to be a full-scale deployment. Indeed, despite the substantial business and technology benefits that IMS will bring, it remains a controversial subject, with many operators struggling to build a business case for its adoption on the basis of just one service. This overlooks the fact that the business case for IMS rests on its ability to deliver multiple services—it is only when operators start to deploy the second, third, and fourth services that it begins to make commercial sense.

Many service providers are therefore hesitant about when—and how—to begin their migrations to IMS. There are concerns that less-than-seamless migrations from legacy systems to IMS will result in customer dissatisfaction and churn—precisely the factors that IMS is meant to address. This is understandable. The IMS implementation path is a step-by-step journey—starting with new services, passing through integration with legacy systems and only then culminating with full-scale deployment.

Clearly therefore, the "everything over IP" world will not happen overnight. The reality for most service providers is that IMS deployments will be incremental journeys, with migrations of existing services to IMS happening step by step. Until full deployment has taken place, IMS must function harmoniously with legacy networks—this convergent approach to service migration means that the revenue-generating value-added services that are already on wireless, wireline, and cable networks will also need to work seamlessly and simultaneously with IMS.

To capture the full potential of IMS during this gradual implementation process, operators must avoid siloed application development.

The value of IMS lies in its standardization of service capabilities, as well as the standardization of device features that enables the delivery of services to any device, anywhere, anytime. Central to this twin capability is the new, layered, data architecture that IMS introduces, optimizing the delivery and provisioning of services (see Figure 1).

However, the lack of specifications at the application layer may lead to major issues—especially in terms of data management, synchronization, and federation across the layers. The fact is that IMS on its own provides no advantage in terms of rapid application and service implementation, so unless this lack of specification is addressed, there will be no improvement in time-to-market for service delivery.

It is important to remember that IMS is a technology that enables optimization of capital expenses (CAPEX) and operational expenses (OPEX). But on its own, it is no more than that. What is needed is a concept that will enable operators to exploit the maximum benefit from this technology while ensuring that it does not become siloed.

Customer data must be seamlessly transferred from operators' legacy network elements and data repositories to the new, central data repository introduced by IMS (the home subscriber server [HSS]). But this is only one part of the process. To deliver a real benefit—by enabling operators to achieve high performance through FMC—IMS must justify its implementation by significantly increasing average revenue per user (ARPU). But how is that goal best achieved?

As we have shown, organizations other than green-field start-ups (which are unencumbered with legacy systems) will not adopt full IMS architectures overnight. Therefore, for almost all operators, there will be a crossover period during which old and new network architectures must coexist harmoniously. Fundamental to achieving seamless interoperability during this phase of IMS deployment will be an infrastructure that can span multiple networks at the same time—preventing IMS from becoming just another technology silo and helping to drive revenue out of this major investment by enabling the delivery of next-generation convergent services from a standards-driven platform, driving down costs, and boosting ARPU.

IMS is designed to support the orchestration of interactions based on session initiation protocol (SIP), the standard for initiating, modifying, and terminating interactive multimedia user sessions. It is a technology framework for delivering and maintaining fixed-mobile service sessions. It is not a technology framework for enabling and implementing the services themselves. In other words, it cannot deliver competitive advantage on its own.

Figure 1

What is needed, we believe, is a strategy that can unite the full potential of IMS with the proven integrating capabilities of the service delivery platform (SDP). By adopting such a strategy, operators will enable a fast-paced service environment and ensure seamless network convergence. IMS orchestrates SIP, strengthening the device-to-core network part of the value chain. The SDP orchestrates IMS and legacy networks, strengthening the core network to operational support systems/business support systems (OSS/BSS) to third-party section of the value chain. Together, they make a strong team.

The SDP orchestrates IMS and legacy networks, strengthening the core network to operational support systems/business support systems (OSS/BSS) to third-party section of the value chain. Together, they make a strong team. The SDP provides an "open," horizontal, and integrating architecture. It standardizes the interfaces linking applications to network elements (OSS/BSS), creates a common set of reusable development tools, and enables content developers full latitude where the creation and deployment of value-added services is concerned. And it has a critical role to play in IMS deployments (see Figure 2). By functioning as the services integration layer across legacy and next-generation fixed and mobile networks, the SDP leverages IMS and other network capabilities to build and deploy enhanced services. As the "glue" between the IMS domains and the legacy domains, it prevents IMS from becoming just another silo. And it allows gradual migration to an all-IMS network combination. Benefits of the SDP solution include the following:

• Unified directory, which complements HSS in terms of customer BSS profile (e.g., services owned, billing status)
• Orchestration between IMS and non-IMS services (e.g., short message service (SMS), e-mail)
• Third-party integration and management

Meeting market demands for new services and having the right infrastructure to meet these demands are two complementary, but very separate, challenges. Operators urgently need to develop strategies for confronting both. The IMS/SDP formula is a powerful solution, enabling operators to build on the "horizontal" integration that the SDP has already delivered to operators worldwide.

For the first time, IMS allows operators to create closely integrated applications and services and the SDP ensures that they can fully leverage this capability by delivering compelling service bundles.

The IMS/SDP provides operators with a standards-driven route to achieving high performance through FMC. But of course, it is not the only way forward. Operators may instead opt to deploy applications on proprietary solutions-especially where time-to-market, and not cost-effectiveness, is the overriding strategic consideration. For example, Microsoft's various devices (i.e., Microsoft TV, Windows Mobile, and the Microsoft Live Communications Server) will all interact "better" with proprietary protocols to back-end Microsoft applications-although they too will benefit from the "orchestration" that the SDP provides.

However, the argument for IMS/SDP as a long-term, value-adding solution is persuasive. Because IMS takes well-established Internet standards (i.e., SIP, DIAMETER, and COPS) and extends them to deliver a carrier-grade infrastructure within a well-defined network, it is likely that it will emerge as the key enabler of FMC (there will be 33 to 66 million IMS subscribers in the United States and western Europe by 2009, according to estimates in the 2006 UBS Investment Research - Q-Series "Communications Equipment: What Is the IP Multimedia Subsystem (IMS) Equipment Opportunity?") And because the SDP is geared to capitalize on these same standards, it has an obvious strategic fit as the bridge to successful IMS deployment.

Figure 2

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