UNI versus propietary interfaces for communication services platforms

User-to-network interface or UNI is just a fancy term for naming the procedures and protocols that communication tools in the user hands (phones, mobiles, soft-phones, IM clients …) use to do their work and establish communicate with the network.
In the pre-Internet circuit based communication world, user devices were very simple, as simple and dumb as possible. Intelligence was supposed to be in the network. UNI capabilities were very limited, as corresponds to a very stable and limited service offer.
Internet turned upside down that approach: the “End to end principle” (https://www1.ietf.org/rfc/rfc1958.txt) translates roughly into “dumb network – smart endpoints”. It is assumed in the Internet that intelligence in the endpoints, and not in the network, that has a very important, but limited role: moving packets as efficiently as possible. Services are deployed in the endpoints, without relying on specific network behaviour. The UNI actually defines the services.
Telco core design (and a good chunk of the business) is based on the “smart network” view. The advent of IP based services thus supposed a revolution, and IMS was designed to mix both approaches: access and core assume the role of the “dumb network” efficiently moving IP packets, whereas the smart endpoints are the IMS, the application servers and the user mobile.
As in the Internet, in IMS the UNI comprises and defines the services. There is little difference between the UNI (client-IMS) and the ICS (app. Server-IMS) interfaces. One example is RCS: a rich, complete UNI that allows to perform all sort of service invocations and combine them with quite a lot of freedom.
Landing from these disquisitions to earthly matters: given that the UNI comprises the services, it is complete, stable, tested …. Wouldn’t make sense to extend the ideas explained above and use it also for communicating with the external, non-RCS world? We propose to use the RCS UNI to communicate web services, enterprise systems, and social networks with RCS.

Obviously the carrier is keeping a role, it's providing a valuable common enabler with its core, and assuring interoperability with other carriers & service roaming, security, and at the same time making easy for the ecosystem create mass market possible adoption for their solutions. WIN-WIN.
Why reinvent the wheel? Why spend money and time on designing new services interfaces when the UNI is there and contains the full service capabilities? Surely it is the better starting point.

Jose Recio