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IMS Analyst Corner

The Impact of IMS on Applications and UIs

By Ronald Gruia

IMS Magazine

The Application View

IMS will allow the creation of new “combinational services” by standardizing the interfaces that applications use toward the core network. This will enable these apps to share information such as billing and provisioning data. So this will mean “smarter” applications, with more information being pushed to the end-users. For instance a “find friend” service combining presence and location can send an SMS whenever a friend from a user’s buddy list IM app happens to be close by, within a certain radius (such as a shopping mall).

Figure 1 illustrates the application architecture in the IMS domain. The SIP (define - news - alert) application server (or app server or A/S for short) represents the service creation and execution platform composed of a SIP applet container that has a

Figure 1

Figure 1

variety of ABBs (Application Building Blocks) such as presence, IM, conferencing and location, among other functions. The SIP app server talks to the S-CSCF (Serving Call Session Control Function) for call control functions via the standard ISC (IMS Service Creation) interface. The SIP A/S also communicates with the HSS (Home Subscriber Server, the main centralized database that holds all the end-user information) via the Sh interface in order to perform various user registration functions. (The authentication protocol used by the Sh interface is Diameter, which is an improved version of its predecessor Radius, an earlier authentication protocol). The SIP A/S provides full access to SIP signaling that is used in communication with the S-CSCF and the HSS. Another requirement for the typical SIP A/S is to provide a set of interfaces for third-party application developers (APIs — Application Programming Interfaces and xDBC — Data Base Connectivity, whether it is Open or Java — ODBC, JDBC). IMS is undoubtedly having
a profound impact in the applications and UIs (User Interfaces) being rolled out by service providers embracing the technology. In the past, the typical communications networks had their telephony services inseparably embedded in the core network switch. The AIN (Advanced Intelligent Network) enabled enhanced services to be built externally from the switches, but SS7 (Signaling System 7) still provided the glue that closely tied these services to the core network. But the separation between the transport, control, and application planes was finally achieved with advent of IMS.

The upshot of all of this architectural discussion is that because the applications share these standard interfaces (which are accessible over a variety of access networks) carriers are able to offer converged services. This is one of the key differentiators of IMS and one that will profoundly impact application design in the future. Instead of pursuing the ultimate killer app, carriers will start rolling out some of these combinational services that can target specific end-user segments. For instance, a gaming app can be combined with an audio conference app, originating a new “game with trash talking” service that can be quite popular within the youth segment.

The User Interface View

The UI represents a fundamental component of the overall solution, as it can be a key determinant of the overall end-user satisfaction and subscriber churn rates. As discussed earlier, IMS will also bring more intelligence to a plethora of endpoints (2.5G / 3G handsets, IP phones, PDAs, PCs, etc.). But how will this added complexity impact the UI for all these devices? The problem is that the existing clients are already far from being ideal. For instance, in the handset world, device complexity leads to the lack of use of some services. In a recent study, Nokia discovered that Asian subscribers only use about 25 percent of the handset functions and that number is even lower in Europe (roughly 10 percent).

Ease of use is a crucial element of a good user interface: without it, applications and/or features are not used as often and subscriber “stickiness” is not as high. So how is it possible to achieve this simplification if it is already so difficult to do so sans IMS? The answer might be within the IMS architecture itself and the richness of the HSS. It is possible that in the future, the ideal IMS UI will be able to Instead of pursuing the ultimate killer app, carriers will start rolling out combinational services
that can target specific end-user segments.
present a set of heuristic rules that will greatly simplify the operation of an endpoint device.

This concept, called adaptive interaction, consists of a rules-based engine that essentially adapts to user preferences. The system changes the way it interacts with a subscriber based on pre-established rules and previous interactions. The key is to personalize the interface to the subscriber, something that operators such as Vodafone (news - alert), (Vodafone Live!), Sprint (Vision) (news - alert), and Verizon Wireless (Get It Now) (news - alert), have been all been moving towards for a long time. But the difference in this case is an enhanced QoE (Quality of Experience), increased subscriber efficiency (due to less time wasted issuing certain commands), and even greater subscriber loyalty.

Adaptive interaction can bring operators closer to the goal of having 70 percent of all functions reachable via a maximum of two key clicks on the handsets. The technology will achieve this goal by being able to fetch subscriber information from the HSS (such as services that the user subscribes to, preference data, etc.) and correlate that with other data (presence, location, time of day) to determine which set of default rules would apply to the typical customer. Of course, the more sophisticated users can change some of these settings, but the idea is to keep everything simple, so for the average subscriber, the system might establish some of these rules based on previous behavior. Some of this intelligence would reside on the network, and some of it on the endpoint device itself.

Putting It All Together

The availability of a wide range of handheld devices means that the applications running on these endpoints have to be as portable and flexible as possible. Therefore, a layered architecture is perhaps the most suitable approach for IMS applications. The three layers are the UI, the application engine, and the protocol stack.
IMS might eradicate the endless pursuit of the elusive killer app.
The UI is the point of communication between the device and the user; it also is a visual representation of the subscriber data that is stored in the application engine. The UI allows end-users to enter information using various modes, including:

• Physical (push-to-talk button);

• DTMF sounds (handset input);

• Graphical (GUI) such as icons;

• Voice (speech recognition and text-to-speech); and

• WWW (web-based client).

The application layer contains the main engine of the service, including all the logic and algorithms used to implement the service functionality. It also has all the necessary data, offering means to store this data either permanently or on a transient fashion. The adaptive interaction logic can also reside in the app layer, in a separate module that could be reused for various applications. The key is to achieve a complete separation from the UI and application layers, thereby eliminating any UI dependencies, and this could be done via a set of APIs. Similarly, the same level of de-coupling is necessary between the app layer and the protocol stack. The rationale in this case is to use distinct protocol stack implementations from distinct vendors with the same app engine. The central theme in all of this is code re-use and the elimination of the dependencies between these three layers. While the concept itself is not the most novel one, given the explosion in the end-user devices in the marketplace and the need to develop applications as quickly as possible, this layered approach will be vital in the IMS world.


IMS might eradicate the endless pursuit of the elusive killer app and replace it instead with the search for the best combinational service that will target a specific end-user segment. Carriers will soon realize that new revenue streams will be possible via the creation of new “blended lifestyle services” enabling users to mix and match services (e.g. push-to-talk, video sharing, voice messaging, instant messaging, voice conferencing, and interactive gaming).

Finally, IMS will bring remarkable increases in edge intelligence resulting in the need for SIP-enabled personal agents managing presence, mobility, and preferences. Simplicity will be an imperative, with information being pushed to available end-users so that they could decide in real-time how to handle an incoming event. In some cases, depending on the time of day, location and presence data, a rules based engine will be there to assist the subscriber.

Ronald Gruia is Program Leader and Senior Strategic Analyst at Frost & Sullivan covering Emerging Communications Solutions. For more information, please visit (news - alerts)

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