The Dark Side of IMS

By Dan Dearing

The IMS architecture has a lot of great things working in its favor; including the fact that it reduces time to market for new and differentiating IP-based services, making it an attractive technology for service providers. Indeed, many providers today have already begun to transform their networks with IMS, recognizing its potential as a flexible way to enhance their existing voice service offerings while also positioning them for future multimedia services. IMS is also hailed as the technology that will enable convergence of all types of communications and ultimately lead to the communications Holy Grail: One number for all services. Pre-IMS, service providers had to build a separate network for each service. With IMS, service providers are now able to pull together for the first time an architecture that enables them to use a single IP network to support multiple services. In doing so, they use the access networks of network operators to reach their subscribers. For example, a Verizon subscriber can subscribe to Verizon FIOS but use the Vonage voice service.

Recently, however, a strange twist has emerged on a story that until now has been almost entirely positive. According to some conspiracy theorists, there’s a dark side to IMS that isn’t being talked about. As part of this theory, IMS isn’t only about converging voice and IP onto one network; it’s also about industry politics and market power. With the advent of converged IP networks, network operators have lost some control; they have had to open up their networks for the first time to other service providers who now have access to their subscribers. But network operators can also harness the power of IMS to gain power and control from a business standpoint by using IMS to deliver services. The theory posits that IMS is really about traditional carriers wanting to control access to users and thus control the services they can buy. Carriers will create “walled gardens” or “islands of IMS” that keep service providers from accessing their subscribers and keep subscribers from accessing the best, most cost-effective services.

The Comfort of the Island Environment

Who is right? Will IMS turn out to be an unalloyed benefit for service providers or will network operators use IMS against them? Equally to the point, why has this conspiracy theory suddenly emerged? Until recently, service provider architects paid little attention to how IMS networks exchanged both session signaling and media with other networks. In effect, IMS networks were being architected as isolated islands with limited interconnections to other service providers. Some believe that this strategy enables service providers to retain control of their service turf and revenue-generating subscribers by keeping third-party providers out. But now, IMS islands are being interconnected to enable user mobility and roaming, and suddenly the competitive environment has changed. Service providers may fear giving up control of their service turf, but they fear being left in the dust by more agile competitors that provide a seamless roaming environment and greater flexibility for subscribers. The fear is well founded; mobility is a key part of the overall value proposition for many of the multimedia services which today’s users want. Beyond the issue of network interconnects is the question of what type of environment network operators will create with IMS. In the new interconnected environment enabled by IMS, all service and device issues depend on user preference. A subscriber can have any type of device and might use any type of application — multimedia, VoIP, IPTV, and more. The operator cannot control which services the user accesses; the provider might even be a competing third party. However, people tend to gravitate to an environment they are comfortable with, and for operators, that environment is the familiar telephony network — an island that requires physical regulators at their interconnect points with other islands.

Conspiracy theorists fear that network operators will cling to their island environments, using IMS to create walled gardens rather than open up trading routes with other islands. The question is then posed, will a “walled garden” approach really be beneficial for operators?

IMS islands are being interconnected to enable user mobility and roaming, and suddenly the competitive environment has changed.

Why Islands Won’t Work

The need for mobility will ultimately make it untenable for operators to maintain IMS islands. Mobile operators were the first to realize the importance of connectivity, which is why IMS has its roots in the mobile world. Now, IMS has become important to service providers and network operators because they can also use it to move forward with important revenue-generating services such as VoIP and the triple play of voice, data, and video. Network operators need to provide the type of flexible and robust services that will attract and retain customers which requires connectivity to other networks. Only by interconnecting islands of IMS can operators give their users access to the services they demand. Operators want the security of knowing they have control over the endpoints and they want to know where the traffic comes from, what type it is, and they want to make sure they can control and manage their network.

What network operators lack from a technology point of view are the tools, diagnostics, and visibility needed to track all types of real-time services — things that are typical in the telephone network but not in the IP network. With the right technology, network operators can retain overall control of their networks AND gain the benefits of connectivity.

Session Management Enables Intelligent Interconnects

Viable interconnections and interconnect solutions are critical for next-generation networks employing IMS. The foundation for IMS interconnectivity is the session border controller (SBC) at the network edge, interoperating in conjunction with a session manager that enables network operators to oversee in a very dynamic way what it happening on the interconnections and apply the business or traffic policies that control them. SBCs act as interconnect points, enabling operators to know who is entering and leaving their network, who is allowed onto the network, and who is allowed to use each service. But SBCs do not operate at the session layer and thus do not provide the type of connectivity required to deal with IMS. This requires a session manager that enables network operators to ask and answer such questions as “Who is doing what on my network? Is the network alert to possible intrusions? How well is my network performing? Is it delivering quality service? Is it profitable?”

Session management can bring light to the dark side of IMS, providing network operators with the comfort level they need to open up their networks.The convergence of services enabled by IMS also makes the network edge much more complex, bringing up issues of how to clearly demark end-to-end service delivery and management. Operators must agree with other operators and service providers what services will be carried across interconnects, as well as on the location and functionality of points of interconnect and handover. Other issues include Internet security threats, interoperability, and support for national variants of services and for legacy services. After taking all of these points into consideration, network operators still have to identify the capabilities and limitations of their CPE. An intelligent SBC can deal with these issues, while a session manager can further simplify the network edge by supporting policies that capture revisions of traditional regulatory and commercial rules, agreement on services to be carried across the interconnect, and agreement on the location and functionality of points of interconnect and handover.

Session Management Brings Light to the Dark Side

In a nutshell, session management at the network edge empowers network operators to connect easily, securely, and scalably with carrier and service provider partners as well as enterprise and residential customers. Session management also enables control as operators can manage, monitor, and bill for VoIP, multimedia, and other real-time sessions that flow through their IP networks. Finally, session management solutions allow the operator to scale and adapt in a rapidly changing market by enabling new business models and new service differentiation.

Session management can bring light to the dark side of IMS, providing network operators with the comfort level they need to open up their networks to the benefits and possibilities of mobility and convergence — and ultimately enabling network neutrality. On a superficial level, living on an IMS island may appear to be comfortable. But mobility is the driving force behind convergence, and network operators that isolate themselves on their own islands, however large, risk losing subscribers who value connectivity and converged services.


Dan Dearing is vice president of marketing at NexTone Communications, Inc. (news - alert). For more information, please visit the company online at www.nextone.com.

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