Chapter 1. Introduction

1.1. Why was IMS Developed?

The communications industry has undergone profound changes over the past decades, driven by similar economic forces across mobile, fixed, and IT/computing networks. Economies of scale and scope have stimulated equipment vendors and operators alike to pursue lower cost technologies, most often based on IP technology. It was within this atmosphere that the IP Multimedia Subsystem (IMS) was initially designed.
At its simplest, the IMS is a set of IP-based technologies that allow for ubiquitous access to multimedia services from any terminal, be it a mobile, landline phone, or PC. It is designed from the same conceptual basis as any mobile network technology, to provide global interoperability between ...

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