IMS � Applications Interoperability and Reuse� Future Reality or Just Hype?

Sometimes it�s the small things that count. Ask a typical mobile phone subscriber if it�s possible for them to have calls routed from their home phone to their mobile service, and you�ll probably get a blank stare. The tech-aware mobile subscriber might say, �Well, first you�d also have to have a mobile account and landline account from the same service provider, and then you�d have to subscribe to that specific service.� But what if your landline provider is Verizon (News - Alert) and your mobile provider is T-Mobile? Why can�t the two services interoperate for the benefit of their common subscriber?

While the previous example is purely hypothetical, it raises a bigger question. Have operators, application service providers, and content providers artificially constrained applications and content to their own service provider silos and hence capped their market? The answer today unfortunately is yes. Common sense says that if a mobile subscriber from one operator wanted to purchase and use a service from a competing landline operator, the landline operator should allow it! Especially if there is revenue sharing potential.

To compete more effectively, legacy and mobile operators are working toward building out the IP Multimedia Subsystem (News - Alert) (IMS) architecture. To be effective, IMS must come complete with the ability to mix and match applications within the IMS footprint and across multiple service provider domains. This article details what needs to happen in the IMS network architecture to enable the re-use of services across subscriber bases.

One of the big promises of IMS is the ability to speed delivery of new applications and new combinations of existing services. That�s the value behind the Service Capability Interaction Manager (SCIM) � it ties disparate applications together and enables application re-use. At a purely technical level, SCIM is part of a Service Delivery Platform (SDP). Its job is to coordinate and control multiple SIP application servers. Each application server is controlling either a whole application, a service primitive or an application sub-feature that can be combined with other primitives to create a new and different service. It sounds great in theory, but it is one of the least talked about IMS elements. Although SCIM has the potential to open up IMS implementations, it can only control application entities in the IMS domain. For this to truly support the mix and match ad hoc application needs of the future, SCIM must support inter/intra-IMS transactions as well as circuit-switched and external silo�d application domains.

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