IMS is breathing a lot of the oxygen in the discussion about next-generation networks, and rightly so considering its promise. At the same time, the IMS picture is unsettled enough to make service providers wonder where the discussion will lead. How should they move to IMS? Can they make IMS investments pay off in the short and long terms? Are large-scale moves toward IMS the right business decision, and if so are they technically feasible? Is it possible to phase in IMS architectures?

The last question is the crux of the IMS discussion:  how to add IMS components to today’s infrastructures to address new service delivery requirements while building a foundation for all-IMS networks. To pay off today and in 10 years, companies must make proportional investments in IMS infrastructures that:

·         leverage and complement the existing PSTN infrastructure;

·         allow new services to be deployed over a fixed/mobile/converged/IP networks.

The most successful next-generation networks will operate as a set of modular services that plug into an architecture that provides common provisioning, billing, maintenance, accounting, and customer service. The less successful infrastructures will be a hodgepodge of point solutions with redundant support systems, poor scalability and high overhead costs.

What would prompt a provider to take the second – and obviously wrong – course? Three factors: an incomplete understanding of IMS; a rush to meet today’s demand for advanced services; and a desire to take advantage of the new technologies and methods that IP-based infrastructures offer.

At the moment, the second factor is dominant. Providers need service offerings that enable them to grab their share of the market for advanced voice, video and data services before the opportunity passes. Their technical staffs want to build these services on IMS-compliant platforms to take advantage of their flexibility and economy. Both of those are logical impulses. They should not, however, lock the provider into a high cost structure that erodes long-term profitability. And they don’t have to. There is a sensible middle ground that sufficiently satisfies all three factors to take  providers to the next phase of their evolution toward IMS.