Evolution of the Network This section provides a synopsis of the various IN phases. As noted in the introduction, a number of stages have introduced additional capabilities | Evolution of the Network This section provides a synopsis of the various IN phases. As noted in the introduction a number of stages have introduced additional capabilities. How they fit together into a coherent view of what currently comprises the IN can be difficult to understand. The focus here is more on the progression of the different phases and what each phase introduces and less on the actual dates on which they were introduced. Figure 11-4 shows the progression. Figure 11-4. IN Evolutionary Progression View full size image The IN began with IN 1 which Bellcore introduced in the 1980s. This brought the SSP to SCP communication exchange into existence. Following IN 1 Bellcore published a series of specifications under the new title the AIN. This series of specifications included version numbers each moved in increments towards a full realization of an IN-centric network in which the SCP had full control of service processing logic at each stage of call processing. This was known as AIN 1. The AIN series created a structured call model which evolved from a simple model in AIN 0 to a much more complete representation in AIN . When the AIN specification was published the ITU-T adopted the IN concept and created a set of standards known as the IN Capability Set 1 CS-1 . The capabilities of CS-1 aligned fairly well with the AIN release. The idea was to publish a series of IN standards that described the set of capabilities added with each release as the IN continued to evolve much in the same manner as the AIN incremental version numbers. The IN CS-2 was later published it aligns with AIN with minimal differences. More recent CS-3 and CS-4 editions have continued to expand the list of capabilities in the IN domain. The following specification series defines the ITU IN recommendations. The x in the series number represents a number from 1 to 9 because each suite contains multiple documents. General Intelligent Network Principles .
