Jun 6, 2007 1:19 PM
The quest for the killer app for IP multimedia subsystem, or IMS, continues at a feverish pace these days, fueled by successes in the Web applications space from companies such as YouTube. Operators and applications developers, based on the Web application development model, have realized that trying to build vertically integrated systems and closed systems will never lead to that elusive killer app, while layering, specialization and openness are key attributes of entities that enable killer apps. With subscribers demanding faster innovation, while accessing the network using many modes and many devices, operators must adopt a different approach to building their network so as to be flexible, nimble and have the ability to experiment with new services so that a killer app may arise.
Operator attitudes toward IMS
One of the major drawbacks of the IMS architecture is that various access methodologies specify a different access network element (see illustration).
Currently, the other drawback of IMS is that the focus is on getting the core infrastructure right rather than on the applications. This is leading to confusion about what applications can be deployed over IMS. More important, it has been leading to discussions about a killer application that will kick-start IMS infrastructure investments.
While on the one hand, that is a prudent approach to planning for capital investment in new infrastructure, there is another school of thought that essentially says that one cannot commission an artist to produce a masterpiece--instead, create the infrastructure to enable multiple applications to be built and deployed on top of it. In fact, since the advent of the Internet, there are more examples of the latter. The way operators have started to deal with the latter scenario is by specializing, thereby making their investments pay off sooner.
However, operators today are waiting for IMS standards to shake out and stabilize. Currently, there are a number of IMS versions that operators have to deal with--3GPP, TISPAN and PacketCable--and the perception is that none of them is complete. There are many initiatives under way to prove each approach to the standard, as well as to ensure that the standards are stable enough to actually start deploying services.
A number of best practices organizations such as the Multi-Service Forum (MSF), and trade associations such as the GSM Association (GSMA), have started to look into not only the interoperability of IMS networks, but also what types of applications can be deployed on IMS. The MSF performs biennial Global Multiservice Interop (GMI) events in multi-vendor and multi-operator settings to explore interoperability issues, as well as look at bridging currently deployed architectures to IMS architectures. The GSMA has a global initiative called IP Interworking to prove global interoperability of IP-based services. These initiatives serve an essential purpose of “debugging” the standard.
Operators eager to embrace IMS have been looking at trial or pilot deployments for evidence of success. These trials provide many benefits--first, the operator obtains an understanding of what type of applications and back-end systems are required to begin service rollout; second, it gives operators an idea of the amount of reuse of network elements possible in the infrastructure part of the network; third, the operator acquires an understanding of service reach challenges by looking at the interconnect issues. These studies provide the operator with good insight into the real cost of deploying IMS infrastructure in their network.
Operators’ motivation for IMS
The complexity of IMS
Implementing IMS is far from simple. Even though the functions and the interfaces have been standardized, the challenge now rests on the integration of these functional blocks into network elements and the interoperability between networks for a given application. There may also be tactical issues with testing the implemented interfaces against compliance with the given standard.
Interop issues in IMS
A larger issue is that IMS-based networks are not going to exist in isolation, and pure IMS networks are going to be hard to deploy. This statement implies bridging between IMS-based networks and older architectures is going to be a huge challenge. The new network has to be in dual-mode, supporting both IMS-based and non-IMS-based services. Operators do not want to strand existing customers as they move to IMS.
VoIP: the IMS killer app
To take advantage of IMS architectures today, operators of all types, including incumbents, independents, wireless operators and service providers, are zeroing in on what they know best--voice. Enhanced telephony services are emerging as the biggest applications opportunity--with VoIP at the top of the list--and operators are looking to bundle services such as voice mail and messaging under VoIP as a means to create subscriber stickiness, increase revenues and reduce the barrier to experiment for the subscriber. IP-based service bundles are easier to deploy and manage, and IMS is an attractive way to achieve this. Other applications of interest include fixed/mobile convergence (FMC), presence and instant messaging (IM).
To make the IMS vision a reality, operators must seek value and deploy interoperable IMS components into their network. Because of the standardization of interfaces, operators can deploy best-of-breed components and solutions. IMS enables service roaming for all services, and hence it is important for inter-operator network compatibility and interoperability for service reach purposes. Deploying the most interoperable solutions for secure peering with other networks, whether IMS or otherwise, is an important consideration for the operators.
It was here all along
Sridhar Ramachandran is co-founder and chief technology officer of NexTone.