SIP Understanding the Session Initiation Protocol Second Edition -- Contents vii -- Foreword to the First Edition xvii -- Preface to the Second Edition xix -- Preface to the First Edition xxi -- 1 SIP and the Internet 1 -- 1.1 Signaling Protocols 1 -- 1.2 The Internet Engineering Task Force 2 -- 1.3 A Brief History of SIP 3 -- 1.4 Internet Multimedia Protocol Stack 4 -- 1.5 Utility Applications 9 -- 1.6 DNS and IP Addresses 10 -- 1.7 URLs and URIs 12 -- 1.8 Multicast 12 -- 1.9 ABNF Representation 13 -- References 14 -- 2 Introduction to SIP 17 -- 2.1 A Simple Session Establishment Example 17 -- 2.2 SIP Call with Proxy Server 25 -- 2.3 SIP Registration Example 31 -- 2.4 SIP Presence and Instant Message Example 33 -- 2.5 Message Transport 38 -- References 42 -- 3 SIP Clients and Servers 43 -- 3.1 SIP User Agents 43 -- 3.2 Presence Agents 44 -- 3.3 Back-to-Back User Agents 45 -- 3.4 SIP Gateways 45 -- 3.5 SIP Servers 47 -- 3.6 Acknowledgment of Messages 55 -- 3.7 Reliability 56 -- 3.8 Authentication 57 -- 3.9 S/MIME Encryption 59 -- 3.10 Multicast Support 60 -- 3.11 Firewalls and NAT Interaction 61 -- 3.12 Protocols and Extensions for NAT Traversal 62 -- References 68 -- 4 SIP Request Messages 71 -- 4.1 Methods 71 -- 4.2 URI and URL Schemes Used by SIP 98 -- 4.3 Tags 102 -- 4.4 Message Bodies 102 -- References 104 -- 5 SIP Response Messages 107 -- 5.1 Informational 108 -- 5.2 Success 112 -- 5.3 Redirection 112 -- 5.4 Client Error 113 -- 5.5 Server Error 123 -- References 126 -- 6 SIP Header Fields 127 -- 6.1 Request and Response Header Fields 128 -- 6.2 Request Header Fields 140 -- 6.3 Response Header Fields 153 -- 6.4 Message Body Header Fields 158 -- References 160 -- 7 Related Protocols 163 -- 7.1 SDP-Session Description Protocol 163 -- 7.2 RTP-Real-Time Transport Protocol 171 -- 7.3 RTP Audio Video Profiles 174 -- 7.4 PSTN Protocols 176.

7.5 SIP for Telephones 177 -- 7.6 Universal Plug and Play Protocol 178 -- References 178 -- 8 Comparison to H.323 181 -- 8.1 Introduction to H.323 181 -- 8.2 Example of H.323 184 -- 8.3 Versions 187 -- 8.4 Comparison 187 -- 8.5 Conclusion 191 -- References 191 -- 9 Wireless and 3GPP 193 -- 9.1 IP Mobility 193 -- 9.2 SIP Mobility 194 -- 9.3 3GPP Architecture and SIP 201 -- 9.4 3GPP Header Fields 203 -- 9.5 Future of SIP and Wireless 204 -- References 204 -- 10 Call Flow Examples 207 -- 10.1 SIP Call with Authentication, Proxies, and Record-Route 207 -- 10.2 SIP Call with Stateless and Stateful Proxies with Called Party Busy 214 -- 10.3 SIP to PSTN Call Through Gateway 218 -- 10.4 PSTN to SIP Call Through Gateway 222 -- 10.5 Parallel Search 225 -- 10.6 H.323 to SIP Call 230 -- 10.7 3GPP Wireless Call Flow 235 -- 10.8 Call Setup Example with Two Proxies 254 -- 10.9 SIP Presence and Instant Message Example 256 -- References 259 -- 11 Future Directions 261 -- 11.1 SIP, SIPPING, and SIMPLE Working Group Design Teams 261 -- 11.2 Other SIP Work Areas 263 -- 11.3 SIP Instant Message and Presence Work 264 -- References 264 -- Appendix A: Changes in the SIP Specification from RFC 2543 to RFC 3261 267 -- About the Author 271 -- Index 273.