8.1 IN today How did we get here?

Today, intelligent network principles are well established in most large fixed public networks, and are controlling many popular high-volume services providing backbone revenue streams for the large network operators.

Most intelligent networks in operation today have their basis in the ITU-T's highly successful CS-1 standard, or the (broadly equivalent) AIN standard in the USA. In order to illustrate the potential for the evolution of the current implementations, we have, in this book, mapped out the range of intelligent network recommendations that have been produced by the ITU-T, which is the main international standards body for telecommunications. Regional variants of IN, such as AIN in the USA and ETSI's Core INAP in Europe have been based on the ITU-T's recommendations.

ITU-T CS-1 was a major early success for IN, but the next standards landmark, CS-2, represented a considerable expansion of detail that has so far proved to be too much for many network operators, although this applies less to newer operating companies who do not have such large legacy overheads. CS-3 consolidated on some of the CS-2 recommendations and started to venture towards broadband networks. We have seen that the recently released CS-4 documents reassess the role of IN against a background of converging PSTN and IP networks. CS-4 seeks to reconcile traditional IN with the IETF initiated activities such as PINT and SPIRIT for supporting services...