The promise of Internet protocol (IP) Multimedia Subsystem (IMS) has been a tale of two "M"s – multimedia and mobility. The architecture in its entirety has been touted as the Holy Grail of convergence, offering a standards-based way to provide multimedia and voice services across platforms, plus security components and one-stop billing and customer service.

IMS was wildly hyped in 2006-2007, but as of today has not been as widely implemented as once predicted. (Skeptics say IMS stands for "implement maybe someday.") The architecture has been branded complex, with interoperability issues and billing challenges, and no killer application with a quick return on investment (ROI).

Though its reputation has been tarnished, IMS still has favor within the industry. Vendors are adapting to become what some call IMS contractors, putting together end-to-end solutions designed to shield service providers from the complexity.

But even the architecture’s strongest cheerleader, the IMS Forum, said in a recent IMS NGN Report Card that the industry might initially see elements of IMS deployed as opposed to a "proliferation of all-IMS networks."

What happened?

To some, the fact that IMS lost some of its sheen in the last year was not surprising. "Analysts were forecasting IMS would be widespread by 2008-2009," said Cassandra Millhouse, director of product marketing for back-office software provider Amdocs. "(So) it’s partly an issue of exalted expectations beyond the ability of the industry to adapt and change."

Millhouse said there have been fewer "tire-kicking inquiries" compared to last year.

When IMS was first introduced, the impression was given that it was an "all or nothing" proposition, said Joe McGarvey, principal analyst, IP services infrastructure, for Current Analysis. "There (has been) a lack of clear applications that are going to drive enough revenue to pay for the cost of converting to IMS," he said. "It was always a fantasy to suggest that operators were going to spend large sums of money on something without a guaranteed payback."

Scratching the surface of IMS exposes an architecture comprising multiple layers, including application, control, transport and access, causing some to cringe at the complexity.

"There are a lot of logical functions within IMS that people put together in systems physically differently," said Keith Higgins, VP of marketing for global strategic technology provider Aricent. "A session border manufacturer might make logical groupings of IMS functions differently than if you went to an edge router company. What we have found is that there are quite a bit of moving parts in IMS, and a lot of interoperability testing (is needed)."

Proof is in the Plugfest?

The IMS Forum and the NGN Forum say the results of five Plugfest interoperability events they have hosted to date debunk much of what they call "misinformation" surrounding IMS. While the specific results are under non-disclosure, future Plugfests are open to non-forum members, and periodic report cards provide a high-level peek into the state of the architecture.

For example, Plugfest participants have assembled a network capable of serving 100,000 subscribers in a day and a half, said Manuel Vexler, IMS Forum technical chairman. "If it was that complicated, it wouldn’t take that little time."

At Plugfests 4 and 5, vendors successfully billed for IMS services, addressing one charge that critics levy against the architecture.

"One of the many fears around IMS is that it is difficult or complicated to charge for IMS services … that it requires operators to completely reshuffle infrastructure billing. Not true," said Dr. Tomas Kovar, worldwide product manager, IUM/RealTime Charging, HP Communications and Media Solutions.

It took HP and Amdocs three days to integrate the former’s Internet Usage Manager charging middleware with the latter’s billing solution. "We managed to prove it was not work for 20 people for 20 years," Kovar said.

Granted, this was a test environment; it involved voice over IP (VoIP) calls over single and multiple domains. But several global telecom operators are using HP’s RealTime Charging solution, including Poland’s Polkomtel, which offers 3G services and plans to roll out new applications on an IMS network.

History repeated?

Boiled down, is the seeming complexity of IMS different from other technologies when they first appeared on the scene? Vexler and IMF Forum Chairman Michael Khalilian don’t think so, pointing to the iPhone.

"It is a great example of something complex inside and simple outside," Vexler said. End users don’t care about the inner workings; they only see the new features and applications, like a touch screen.

"(Traditional handsets are) obsolete," Khalilian said. "It didn’t happen in one year. It happened that one company with great marketing and great expectations from consumers stood up and separated themselves, and now everyone is following. (We) need a couple of key leaders and service providers and vendors to break the barriers."

VoIP is another example, analyst McGarvey said, noting that the cable industry adopted it to remain competitive. "If cable providers want to compete with some of the other offerings out there, including the things Google is offering, or Yahoo, they need to adopt an architecture that will allow them to deliver multimedia."

IMS inside

IMS promises the ability to implement new, rich services rapidly in a plug-and-play environment and offers security and management capabilities. "The IMS infrastructure provides many features implicitly as an automatic part of the network," Kovar said. "End subscriber services are available anywhere, anytime, independently of the device they are using."

There also is what Higgins calls the death of the walled garden. "Mobile networks are not built with the capacity and multimedia functionality to deliver content that has been created on today’s Web sites," he said. "There is a lot happening to bring IMS into the mobile device in a way that compliments open operating systems."

Yet some, including Global Crossing, a managed telecom solutions provider, are not sold on the idea of IMS. "It’s not so much that there isn’t a killer application, but that the killer application requires IMS. It doesn’t," said Adam Uzelac, the company’s director of converged services architecture.

Global Crossing has a session initiation protocol (SIP)-enabled network. "We do have the core foundation to build IMS upon, but still we are struggling to find a justification to put IMS in the network," Uzelac said.

Others, however, say the decisive point for IMS is that it is standards-based. "If you are going to base your next generation service delivery infrastructure on SIP, it would make sense to be compatible with the standard," McGarvey said. He made a comparison to the universal interfaces between telephone networks, be they fixed, wireless or VoIP.

"Only with a standard will multimedia applications work the same way," he said.

Not ‘all or nothing’ any more

In fact, even though Global Crossing feels IMS as an architecture is too "top heavy," it sees merits in certain elements. "We have defined ‘IMS Lite,’ which cherrypicks some of the things we thought were good in the architecture," Uzelac said. (See sidebar.)

This seems to be a theme song for IMS right now.

"There is so much involved in IMS," said James George, president, American Cable Services, and a member of the board of the IMS/NGN Forum. "I am only doing certain aspects. No one is launching 100 percent of what IMS proposes."

George said he has installed "throw-away" headends for quick market entry. "As the technology equipment vendors catch up with what IMS is proposing, then I can start changing it."

A structured wiring provider that also serves as a small private cable operator, American Cable Services already offers various home networking services as well as IPTV and plans on wireless perhaps within a year.

Among larger cable operators, Cox has been one of the few to mention IMS by name, perhaps not surprising given that it’s independent when it comes to wireless. But tellingly, in an interview with CT published last November, then SVP and CIO (and now SVP Technology) Scott Hatfield also used the word "evolution" in reference to IP, IMS and service oriented architectures that can enable a less "siloed" and more unified service delivery.

A Cox spokesperson declined comment on timetables for IMS deployment, but simply said, "We’re still a big fan of the technology, and we are moving down that path."

As for cable as a whole, mobility could be the driver, said Mike Cooper, vice president of marketing and strategy convergence for Alcatel Lucent. "Many of the bids coming in from cable are talking compliance around IMS from a 3GPP perspective and also PacketCable 2.0."


On the other end of the spectrum from IMS Lite are end-to-end solutions. "The good news is that there are IMS general contractors in the world," Higgins said.

"Equipment makers … are trying to take complexity and cost out of adopting IMS by bundling it into configurations that are more manageable," said Current Analysis’ McGarvey. "IMS must have 30-35 elements it defines and interfaces between all of them. All of those interfaces are hidden from the operator."

Cooper offered an analogy. "In the early days of switching, (the industry) said, ‘Let’s not sell the switch but the total solution so the switch interoperates and tests with other protocols and equipment in the network.’" He feels the same idea goes for IMS. In fact, it was recently announced that France’s Hub Telecom will use Alcatel-Lucent’s turnkey IMS solution.

However, bundled IMS solutions, in general, override one of IMS’ benefits – the promotion of multi-vendor deployments. "At the same time, the practical, pragmatic things always sort of trump the ideal," McGarvey said. "It is still IMS, but proprietary IMS."

Monta Monaco Hernon is a contributor to Communications Technology. Reach her at
[email protected].

Sidebar: IMS Lite?

Since IMS is no longer thought of as an "all or nothing" proposition, some are internally defining "IMS Lite." Elements of interest are the SIP call session control function, the home subscriber server, and the service capacity interaction manager. And from the application side, the concept of presence has proven attractive.

"I know at least one cable operator that is using this approach to provide subscribers to its VoIP service with a browser that provides an active address book with presence and the ability to initiate voice calls with a mouse click," said Joe McGarvey, principal analyst, IP Services Infrastructure, Current Analysis. These are possible to deliver through SIP, but an IMS setting is needed to extend them across devices and networks.

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