Sinnreich H., Johnston A.B. Internet Communications Using SIP. Delivering VoIP and Multimedia Services with Session Initiation Protocol

Издательство John Wiley, 2008. - 409 p.About 10 years ago, the first drafts describing the Session Initiation Protocol (1996) were published, with the rather modest ambition of setting up multicast groups for multimedia conferences. In the intervening decade, a draft of about 20 pages has turned into an ecosystem of dozens of RFCs, hundreds of Internet drafts—and several books, conferences, and a magazine. It has become difficult to get a feel for the overall landscape, to distinguish the important core concepts from the niche applications. This book offers a detailed, technically informed, yet accessible, introduction to the overall SIP ecosystem, suitable both for someone who needs to understand the technology to make strategic decisions and implementers who need to build new components.SIP is part of the second wave of Internet application protocol. While the first wave largely focused on asynchronous communications (such as e-mail, and data transfer), this second wave introduces the notion of interactive, human-to-human communication that allows integration with any media, not just voice. As SIP and interactive communications have matured, the goal for human-to-human communication has shifted. Initially, cell phones promised voice communication at any time, at any place. Multimedia communications, on PCs and maybe emerging cellular networks, allow us to add any media. However, the any time, any place, any media can also turn us into slaves of our communications devices, interrupting our ability to think, to eat in peace, and to meet in person. Thus, our goal has to be to design communications technology that offers the right media, at the right place, and at the right time. With some of the advanced functionality of SIP, such as presence, location-based services, user-created services, and caller preferences, we can get closer to creating communication systems that support our work and enhance our personal life.With new communications technologies, there is always the temptation to mimic the old. E-mail inherited aspects of the interoffice memo and fax; web pages attempted to look like newsprint and brochures. However, in VoIP, there is the particular temptation to recreate old technology features, as interoperability with the old PSTN will remain important for at least another decade.Fax-to-email gateways were never quite as important as VoIP-to-PSTN gateways. This emphasis on interoperability with 100-year-old technology has provided a financial motivation—provide the same service more cheaply. However, this may also hold back the promise offered by Internet-based multimedia communications, such as the integration of presence, the ability not just to communicate by voice and maybe video but also to share any application, or the ability to customize the user experience and integrate interactive communications with existing Internet tools and applications. Just as most microprocessors are embedded in household appliances and cars, not desktop PCs and laptops, we might find that Internet-based voice and multimedia communications will be integrated into games, appliances, and cameras, or be hidden behind a link on a web page, rather than dialed by name or number. As for many of the most innovative applications, users will likely not even consider them phone services at all, but extensions that make some other application more productive or more fun.This book is like a good tour guide to a foreign country. It doesn’t just describe the major sites and tourist attractions; it lets the reader share in the history, spirit, language, and culture of the place. Natives write the best tour guides, and the authors have been living and working in SIP land since it was a small outpost in one large country called the IETF. The authors have served as ambassadors in lands near and far, but have also made major contributions to the development of this part of the Internet landscape, always reminding others of the original goals of the first inhabitants. After taking the tour, the reader will be ready not just to show off a stamp on a passport or certificate but also to contribute to new modes of communications. SIP land is still young and needs lots of pioneers who can push the frontiers of Internet-enabled communications. There might not always be gold in those hills, but enriching human communications will always be its own reward.Internet Communications Enabled by SIP.
Architectural Principles of the Internet.
DNS and ENUM.
Real-Time Internet Multimedia.
SIP Overview.
SIP Service Creation.
User Preferences.
SIP Security.
NAT and Firewall Traversal.
SIP Telephony.
Voicemail and Universal Messaging.
Presence and Instant Messaging.
SIP Conferencing.
SIP Application Level Mobility.
Emergency and Preemption Communication Services.
Accessibility for the Disabled.
Quality of Service for Real-Time Internet Communications.
SIP Component Services.
Peer-to-Peer SIP.
Conclusions and Future Directions.