Mobility and Single Sign-On
By MortazaviBlog on Jul 02, 2004
One may argue that mobile telecommunications operators already have a form of single sign-on operating under the covers.
As the "mobile station" (the technical, GSM term for the mobile phone) moves, it needs constantly to access distinct resources (or services).
When a mobile station moves, the cellular tower giving it access to the public land mobile network (PLMN) will eventually hand off to the next cellular tower. The radio network server will use signal strength comparisons between the towers as an indication of when and where hand-off needs to occur.
However, single sign-on to network resources and services is a truly general concept in need of a more broad treatment. In fact, the Liberty Alliance, a standards organization has addressed the problem of single sign-on in its ID-FF (identity federation framework) set of specs.
So, where does the economic necessity come from?
Mobile telecommunications providers are focused in providing connectivity, access, identity and other voice and data services to their customers. From their point of view, a service is a kind of network interaction for which the subscriber is willing to pay. However, as we move to the a mobile age filled with perviously unimagined forms of voice and data communications, various "services" will need to be composed to provide the required features in a sophisticated and billable service.
A simple example may help.
Let's say you're a network operator serving 15 million people, offering them Multi-media Messaging Service (MMS) capabilities. Your subscribers are carrying mobile stations that can take pictures, which they can send to others through MMS or other means. Your subscribers also receive multi-media messages, say pictures or video clips, from friends, family or other services (e.g. sports, whether, etc.) to which they have subscribed.
What if your subscriber wants to maintain an album for all these in-coming and out-going multi-media messages? Should you be providing that service or should you be "outsourcing" it to another business that specializes in maintaining large multi-media albums and libraries? You'll probably choose the latter course because the business of providing digital albums for multi-media content is not within your core competency. The album business is a separate business. In fact, your subscribers will want to access their albums in multiple ways and will probably want to preserve a distinct identity with their album provider.
This example simply shows that the decision to host a broad SSO solution can be an economically rational decision for the mobile telecommunications operators simply because economics of sophisticated services will push them to "sub-contract" or "outsource" many of the "services" which they will have to compose into a billable service.
In the presence of sophisticated service composition, one would need a very good SSO and identity model. Hence, the advent of the Liberty Alliance.