The other general point of agreement is that service providers need new revenues now — particularly fixed or wireline service providers. Voice-over-IP (VoIP) players are having to very quickly find new points of differentiation, and traditional voice operators are seeing wireless services eat into their core revenues. Both are looking to fixed/mobile convergence, which has rapidly become a primary driver for deployment of IMS technology.

“Right now most of what the service providers are focusing on falls more in the fixed/mobile convergence space,” McGarvey said. “They are not looking for new-fangled services so much as they are trying to bridge the services layer between the mobile and the fixed. That means more than just dual-mode handsets; it means new applications, like having the four-digit dialing on my mobile phone and on my desk phone.”

IMS helps the wireline market address mobility, said Grant Henderson, executive vice president of marketing and strategy and co-founder of Convedia, a venture-based company in the multi-protocol IP media server space.

“IMS came out of the 3GPP, which is all about the evolution of the mobile market, but it is being embraced by wireline carriers because it brings mobility into their market. The VoIP networks that are built today share a lot of common elements with IMS — they are essentially IMS-ready.”

That means that new services are not about simple voice replacement but include multimedia capabilities, he added. For example, in Asia, where congestion and traffic make casual social encounters more difficult, service providers have added voice to gaming applications to create multimedia games that go beyond the shoot 'em up variety to include mah-jongg and more, Henderson said.

“The architecture they are using is very IMS-like,” he said.

IP Unity has deployed its media servers and application servers worldwide in IMS-like architectures, said Keith Bhatia, the company's chief technology officer. The company is involved in five trials, three of which involve fixed/mobile convergence.

“We are adding interfaces that are IMS-compatible, using the [Home Subscriber Server, a key IMS database] and taking the media server and expanding it to be a true media resource,” he said. “And we are taking the application server and adding multiple applications.”

Where IMS first comes into the network varies by type of service provider, said John Weald, chief technical officer of Sylantro Systems, whose SIP server is deployed in IMS and non-IMS settings. For example, IMS has become the reference architecture for VoIP players moving forward, but is more viewed as an edge play for wireless providers, to add the services they need without disrupting the core network, which remains TDM and SS7 based, he said.

There is general agreement that where IMS becomes important is when service providers start layering on applications that need to use the basic building blocks of IMS that are intended to be reusable through open interfaces. Without seamless use of these core functions, the danger is that service providers will merely recreate today's service “silos” — where each service has its own components and interfaces to billing and operations — and lose the promised efficiencies of IMS.