Since authentication and registration were already
concepts implemented in GSM, the 3GPP community felt these functions were essential
in any IP implementations, and therefore set about to provide the architecture to
support these functions at a minimum.
The IMS provides both wireline and wireless operators with a path to evolve their
current networks to an all-IP services network, while enhancing their current security.
Certainly many wireline networks would benefit from authentication as well as the call
session control functions defined by IMS.
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Chapter 2
Moving from Legacy to Convergence
As should be expected, migrating a network from a legacy architecture to a nextgeneration
technology is not a small undertaking. It involves so much more than simply
launching a few platforms, connecting up the circuits, and calling it a network.
There are countless systems and applications that are all connected in some fashion
to the network as well as the various network elements. These systems must somehow
interoperate with all the other systems and applications, to ensure a seamless transition.
Throughout the entire process of transitioning the network, the operator must
somehow ensure that subscribers never experience a degradation in service, and that
all investments are protected and future-proof.
When the telephone companies of the world implemented Signaling System #7 (SS7)
and the Intelligent Network (IN), their intentions were certainly noble.
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