IMS no panacea for service creation

But there is less agreement on how prepared the industry is to address the broader service creation challenge that will enable the full benefits of IMS to reach service providers.

“[IMS-based applications] should not be professional services projects,” Personeta's McIlvane said. “That's what we see in the space today. IMS is supposed to provide reusable resources. But service brokering today is about professional services.”

However, the difficult integration and service brokering work has not been done to make it possible for all the reusable components of IMS to be knit together in multiple different ways so that services work seamlessly over different access networks and different call models, as is the goal of the new architecture.

“The challenge is how to bundle together the next-generation services from different application platforms,” he said. “For example, a unified voice mailbox would need to operate with an enterprise communication service, a home broadband service and the [public network]. These are the kind of services that will drive revenues and mind share and leadership and differentiation.”

One key element for accomplishing this, the service capability interaction module (SCIM), is still not well-defined under IMS standards, analyst McGarvey said. One critical role it will play is that of service broker between the existing intelligence of today's SS7 networks and the SIP networks of the future.

“You can put a gateway in and bridge SS7 to SIP to leverage the existing intelligence,” McGarvey said. “SCIM acts as a service broker between the legacy application servers and the new network. Under IMS, a lot of the feature sets of today's softswitches become application servers.”

Ideally, a service provider would be able to deploy an HSS and multiple service control functions from different vendors and a SCIM from another, but that requires further definition.

“It would be nice to have the flexibility at the highest granularity of the network,” McGarvey said. “The more integrated something is, the less open it is going to be, and the less opportunity for interoperability there is.”

There is not yet agreement, however, even on where SCIM will go in the network, said Jeff Liebl, software vice president of Ubiquity, which makes SIP servers. It could exist at the switching fabric level or where the service itself is actually managed.

“It's part of a network architecture debate at the moment,” he said. “You have silo or point applications that exist today, and IMS moves the whole operator environment more toward a horizontal layer, so there is one platform on which multiple elements are engaged.”

Without the service mediation function, however, there is some danger of creating IP service silos that merely replace the legacy service silos that exist today. There are sharp differences of opinion as to how and when IMS evolves to address this issue.

“There is a tremendous amount of confusion,” said Alex Doyle, senior director-solutions for BroadSoft, which is commercially deploying IMS today. “People think IMS will solve the feature interaction problem, but it won't do that any more than any previous architecture. What it does is bring a degree of order to your network. Feature interaction is still really the problem in any service creation environment, but IMS gives you an orderly platform that helps manage it a little better.”

Different equipment vendors are taking different approaches to tackling the near-term and longer-term issues of feature interaction to enable service creation today. BroadSoft is using a pre-standard SCIM in its deployments and supporting multiple applications on its platform. Ubiquity has what Liebl calls a “horizontal SIP server” to host multiple applications. LignUp is creating a Web services-based play that is network-independent and evolves to IMS, Nethercott said.

Personeta has created a service delivery environment (SDE) that directly addresses the service brokering and mediation function, as well as back-office issues that have historically slowed the deployment of new services, said Avraham (Bibi) Rosenbach, co-founder and executive vice president of business development.

“There are application servers right now that each come with their own service creation,” he said. “The SDE is a more comprehensive approach. It is actually three pieces — the execution environment, the service creation piece and the SCIM.”

Since service providers are under pressure to produce new services today, it is likely they will proceed with what's available now and work to get to a more standardized IMS environment going forward, said Kenneth Osowski, vice president of marketing and product management for Pactolis.

“If the vendor architects to an open services architecture and continues to fine-tune the SIP stack for compliance, there shouldn't be too many changes to the call flows when new things are added,” he said. “We're also adding Diameter, the IMS protocol that talks to the subscriber database. That's a key change.”

Because of the massive nature of the change, it is also likely to happen over a longer period of time than today's hype around IMS would lead one to believe, said Vaughn Eisler of Tekelec, which is developing IMS systems and is a major provider of SS7 components as well.

“Service providers have invested billions in SS7, and that is not going away any time soon,” he said. “Over the course of time — five to 20 years — there will be a downturn in [legacy] technologies and an upturn in IMS.”