Internet Communications Using SIP Delivering VolP and Multimedia Services with Session Initiation Protocol John Wiley & Sons, Inc. NEW YORK CHICHESTER WEINHEIM BRISBANE SINCAPORE TORONTO
Contents Foreword Preface Acknowledgments XV xvii xix Chapter 1 Chapter 2 Introduction Problem: Too Many Networks Network Consolidation Voice on the Net SIP Is Not a Miracle Protocol The Short History of SIP in This Book for Telephony IP Communications Enabled by SIP Internet Multimedia Protocols The Value of Signaling Addressing SIP Capabilities Overview of Services Provided by SIP Intelligent Network Services Using SIP: ITU Services CS-1 and CS-2 Presence and Instant Communications 1 l 2 2 3 3 4 5 5 7 8 8 9 11 12 13 15
X Contents Chapter 3 Chapter 4 Chapter 5 Service Creation Mixed Internet-PSTN Services ENUM SIP Security SIP Orphans SIP Interworking with ITU-T Protocols What SIP Does Not Do Overview of SIP Services by Market Segment Commercial SIP Products More Work Ahead Architectural Principles of the Internet Telecom Architecture Internet Architecture The Internet Standards Process Protocols and Application Programming Interfaces Internet Multimedia and Conferencing Introduction Freshening Up on IP Internet Multimedia Protocols Multicast Protocols Transport Protocols Internet Services Media and Data Formats Multimedia Server Recording/Playback Control Session Description Session Announcements Session Invitation Authentication and Key Distribution Summary SIP Overview What Makes SIP Special SIP-Enabled Network Watching How Sausages Are Being Made What SIP Is Not Introduction to SIP Elements of a SIP Network SIP Functions Address Resolution Session-Related Functions Non-Session-Related Functions 19 20 21 22 22 23 24 25 27 28 29 33 33 35 37 37 38 39 39 40 41 41 43 44 46 48 48 51 51 52 55 56 57 57 60 62 63 77
Summary Chapter 6 SIP Service Creation 87 Services in SIP 87 Service Example 88 New Methods and Headers 92 Service Creation Options 93 Call Processing Language 94 SIP Common Gateway Interface 98 SIP Application Programming Interfaces 99 SIP and VoiceXML 100 Summary 101 101 Chapter 7 User Preferences 103 Introduction 103 Preferences of Caller 104 Example for Contact 105 Example for Accept-Contact 106 Example for Reject-Contact 106 Preferences of the Called Party 107 Server Support for User Preferences and for Policies 108 Summary 108 108 Chapter 8 Security, NATs, and Firewalls 109 Basics of SIP Security 110 Authentication 110 Encryption 111 Digital Signatures 113 Network Address Translators 113 Firewalls 116 ALG, Firewall, and NAT Traversal 117 Privacy Considerations 120 Design of a Secure SIP Network 123 Summary 124 124 Chapter 9 SIP-Based Telephony 127 Basic Telephony Services 127 SIP and PSTN Interworking Gateway Location and Routing 128 Enhanced Telephony Services 137 Call Control Services and Third-Party Call Control 141 Problem Statement 142 84 85
xii Contents SIP Third-Party Call Control 144 Summary 148 1 Chapter 10 Voice Mail and Unified Messaging 151 Problem Statement 151 Example of Unified Message Operation and Architecture 152 RTSP-Enabled Voice Message Retrieval 154 Message-Waiting Notification 154 Summary 159 159 Chapter 11 Presence and Instant Communications 161 The Emergence of Instant Messaging 161 The IETF Model for Presence and Instant Messaging 162 Security for Presence and IM 164 The Common Profile for Instant Messaging 165 Presence Service 166 Instant Message Service 167 Why SIP for Presence and Instant Messaging? 167 New Services Based on SIP for Presence 168 Ponte Calüng 168 Avoiding Unsuccessful Calls 169 Automatic Call-Back on Presence 169 Legitimate Tracking of the Workforce 169 Replacing Traditional Telephony Services and Devices 169 Architecture for Instant IP Communications 170 Basic Call Flows for SIP IM 173 SIP for Instant Messaging 174 Lightweight Data Formats 175 Communications Based on Presence 175 177 Chapter 12 SIP Conferencing 179 Introduction 179 SIP Conferencing Models 180 Ad Hoc and Scheduled Conferences 183 Summary 185 185 Chapter 13 Mixed PSTN and Internet Telephony Services 187 Introduction 187 Click-to-Connect: An Action on the Web Initiates a Call on the PSTN 188 Internet (Alert for) Call Waiting: An Incoming PSTN Call Is Signaled on the Web 188
Contents xiii Introduction to PINT 189 PINT Extensions to SDP 190 Examples of PINT Requests and Responses 191 Introduction to SPIRITS 193 Call Flows for Internet Call Waiting 194 IN-SIP Gateway and Services 196 Enhancing or Replacing IN with SIP 198 SPIRITS and INAP Interworking 198 Summary 200 200 Chapter 14 DNS and ENUM 201 Introduction: DNS and Directories 201 Addressing and DNS 202 URIs and URLs 202 The Domain Name System 202 DNS and Directory Security 207 DNS-Based Directory Services Using SIP 210 Single Contact Address 211 Three-Level Directory Systems 212 Summary 219 219 Chapter 15 SIP Mobility 221 Mobile Networks 221 Dimensions of Mobility 222 Mobility Examples 223 Mobüe IP 223 Roaming Users 225 Remote Registration 225 SIP Precall Mobility 225 SIP Midcall Mobility 229 Personal Mobility 229 SIP Service Mobility 230 Summary 231 231 Chapter 16 AAA and QoS for SIP 233 Options to Achieve QoS 233 Separation of Network and Application Signaling 234 Network Models for QoS 235 Single Domain QoS 235 Interdomain QoS 237 The Application Policy Server 239 Interdomain Signaling for Quality of Service 241
xiv Contents QoS Options 241 Summary 244 245 Chapter 17 The Component Server Architecture 247 Services for IP Telephony Gateways 247 The Integrated Applications Environment 251 Integration of Web, Email, and Voice 254 Examples of Integrating Component Services 255 CollectingofDTMFDigits 256 Interactive Voice Response 258 Scheduled Conference Service 258 Voice Mail 260 Summary 261 261 Chapter 18 Conclusions and Future Directions 265 TheFutureofSIP 265 Future Services 265 Summary 267 267 Glossary 269 Index 275