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Preface
SIP follows the fl exible Internet approach that advocates moving intelligence to
the endpoints and keeping the network as simple as possible.
During that time, I became convinced that understanding, even if it is at a high
level, how SIP software works helps to understand its simplicity, fl exibility, and
potential. And that is the reason why, when years later I decided to write a book
on a state-of-the-art approach for multimedia communications, I went for an
approach that combined theory with practice. And the result is this book.
Approach
This book ’ s aim is to let readers understand what Internet multimedia
communications are and how they are enabled by using the Session Initiation
Protocol and other related technologies. The approach I have taken in writing
this book has three main characteristics.
First, it is Internet-orientated . That is, it is focused on the Internet technologies,
protocols, and practices for delivering these services. In the last two chapters, it
also touches upon how these Internet technologies can be used in controlled
network scenarios such as those present in telecom operators ’ multimedia
networks. In fact, the bodies involved in the standardization of telecom networks,
such as ETSI or 3GPP, have adopted the ideas coming from the Internet in order
to design the next generation of telecommunication networks.
Second, it follows a fully modern and up-to-date approach where the latest
Internet developments are analyzed and discussed. In addition to providing a
thorough explanation of the basic concepts, it also presents the most recent
proposals for utilization of SIP and related technologies in the remit of multimedia
communications. The book tackles new and innovative technologies and services
such as MSRP, NAT traversal, STUN, ICE, session border controllers, TCP-based media
transport, XCON conferencing framework, media server control, GRUUs, RPID,
latest approaches for RTP security, XCAP, Text over IP, remote call control, fl oor
control, conference control, Fax over IP, enhanced identity management, IMS,
TISPAN next generation networks, voice call continuity, IMS centralized services,
and so forth.
Following a modern approach implies that the book contains not just references
to offi cial standard or informative documents (e.g., Request For Comments), but
also many references to the latest IETF Internet Drafts that represent current
work in progress.
Third, the book is unique in its kind by the fact that it not only contains theory
but also practice . The practical nature of the book is twofold. On one hand, the
book tackles multimedia service creation, both at SIP level and at media level.
It contains a comprehensive description of the state-of-the-art technologies