At the end of last century—to quote Thomas L. Friedman’s excellent book, The World Is Flat—I was part of the unflat old world, specifically the old telephony world. I was reading (and listening to) the new flat world boys coming at the speed of light to re-do and improve things in months, weeks or even days that had previously taken us years to develop.

I was able to witness the initial days of the Voice over Packets (although, to be precise, voice was over packets when it became digital, years before), the initial trials and the early deployments of Voice over ATM and over IP. It was the time of the “Internet bubble” and a lot of fast innovation was happening, with many new small and smart start-up companies created, mainly in the USA and Scandinavia. It was a beautiful, creative time.

However, things were not so simple. The initial efforts to quickly replace the old telephony (SS7) world failed, and only the strongest companies survived. Once again, the technique of copying and using the best of both worlds (SS7 and IP), was used. SIP protocol was born (congratulations SIP!). It was, and still is, difficult to find people really skilled in both (SS7 and IP telephony) areas, and interdisciplinary teams were formed, with people bringing what they had, in many cases with high personal effort. I was lucky to be part of one of these teams in IETF (with a very modest contribution) and learned a lot from it.

Such technologies have evolved a lot and, still, there are not many people with complete knowledge of the SIP (and Internet Multimedia) technology, including all aspects: from theory, prototyping, and development, to implementation. Rogelio is one of the few people I know with such broad (covering theoretical and practical aspects) and deep knowledge, based on years of work in different managerial positions in the communications area (steering and inspiring key projects in different technology units).

I strongly believe the Multimedia Internet (mainly mobile and ubiquitous) is here to stay. It is starting to happen, and I honestly do not know where it will take us within the next five years, but I dream of a richer instant multimedia communication, making our lives more comfortable, allowing us more time to enjoy the company of our family and friends.

For such dream, I am sure that protocols like SIP are the way forward. But they are nothing without innovative, high quality applications adapted to our (customer) needs (and with a sustainable business model).

This book covers both areas needed to move into my dreams. It covers in depth SIP (and many IP related) protocols and networks and how to develop applications using its full potential. This is the reason I like Rogelio’s book and I think it is an excellent guide to any engineer willing to plan, deploy or operate a SIP network and to any developer wishing to build efficient applications making use of the potential of a SIP network.

I am sure you will enjoy reading the book and I hope it helps you to contribute to enrich the Multimedia Mobile Internet world.

When the Internet was developed in the 1970s of the previous century (long before my personal involvement with this technology!), it was targeting data services. Remote users could—in a convenient way according to the standards of that time—share electronic data files, establish simple message exchange sessions or establish machine-to-machine data communication sessions. Even so, the Internet had limited usage and was applied mainly in the academic world and by research institutes. The ARPANET, as the data connection network was known in those days, was gradually replaced by the NSFNET. The main transmission protocol used by NSFNET remained TCP/IP, inherited from the ARPANET. TCP and IP have undergone a number of iterations up to the current TCP v4, IP v4 and IP v6.

Along with the rapid growth of the number of Internet based applications, initially mainly person-to-content applications, emerged the concept of Internet based communications. Obviously, all Internet based applications constitute some form of communication. However, this new trend relates rather to person-to-person communication. One prominent example of this is Voice over IP (VOIP) between two Internet users. There are currently a large number of VOIP applications in operation on the public Internet. A current trend is to extend VOIP to include also multimedia, i.e. Internet multimedia communications, encompassing voice, video, text etc.

The Session initiation protocol (SIP) was developed by the Internet engineering task force (IETF) as the artery of Internet voice and multimedia communications. SIP is considered the successor of the H.323 protocol which was developed by the ITU-T for similar application.

The third generation partnership project (3GPP) has adopted SIP as the protocol for the IP multimedia system (IMS). This underscores the faith that the industry has in the long-term usability of SIP for multimedia communications. It also gives substance to the expectation that there will be widespread deployment of SIP-based communication for the foreseeable future. Thorough understanding of SIP is therefore quintessential for anyone involved in Internet based multimedia communication such as IMS. It must be emphasized here that Internet based communication encompasses the public Internet (e.g. peer-to-peer VOIP), enterprise networks (e.g. IP based office communication) and telecommunications networks (e.g. IMS). SIP and the accompanying media transport protocol RTP, have even found their way in the more traditional architectures like Wireline networks and mobile networks.

The book from Rogelio Martínez, Internet Multimedia Communications Using SIP, is an excellent source of information for anybody working in this field. During the period that Rogelio and I were closely involved in the development of architecture of an Internet based communication system, I came to appreciate Rogelio’s wealth of knowledge in this field of technology. This book leaves no doubt about that! The book takes the reader through essentials of VOIP and IMS. It has an easy-to-follow step-by-step approach, starting with a brief history of the Internet. When reading chapter 1 of the book, one will almost feel part of the Internet development scene. The reader is then taken gradually from ‘plain SIP’ to advanced techniques. Brand new topics like Presence, IMS messaging and multimedia conferencing are covered. NAT Traversal, being an important issue when running SIP through border gateways, is extensively described in a separate chapter. Quality of service is traditionally a cornerstone of the telecommunications industry. Developers of Internet based communication systems will therefore gain ample advantage of the dedicated chapter on that topic. User identification and data security are essential to any communication system and are therefore covered in-depth as well. The book shows that there is continuing development in these areas. The reader is further enticed to put theory into practice. This is accomplished through the JAVA based SIP terminal that the reader is invited to build, using the example software code contained in the book. This combination of theory and practice makes the book unique in its class.

This book is an excellent contribution to the Internet communications industry. It not only provides a good explanation of the fundamentals of VOIP and IMS, but it also includes ample references to relevant standards for further reading. This book is therefore strongly recommended to anyone who needs to build up knowledge in this area of technology.

The book further strikes a bridge between the ‘old technology’ (GSM, Intelligent networks) and the ‘new technology’ (IMS, SIP). Having worked in the area of GSM and Intelligent networks for a substantial number of years, I appreciate the links that one can draw between well-known techniques and principles from GSM on the one hand and methods applied in the Internet communications on the other hand. Quite appropriately, the book closes with a dedicated chapter on IMS, placing SIP and related techniques in a mobile context and showing the additional challenges that the mobile environment brings. The book is therefore also an ideal guide for professionals who come from a telecommunications background.