Internet Communications
Using SIP
Delivering VolP and Multimedia Services
with Session Initiation Protocol
Second Edition
Henry Sinnreich
Alan B. Johnston
WILEY
Contents
Foreword xxi Acknowledgments xxiii
Introduction xxv Chapter 1 Introduction 1
Problem: Too Many Public Networks 1 Incompatible Enterprise Communications 4 Network Consolidation: The Internet 4
Voice over IP 5 Presence—The Dial Tone for the Twenty-First Century? 6
The Value Proposition of SIP 6 SIP Is Not a Miracle Protocol 6 The Short History of SIP 7 References in This Book 8 SIP Open Source Code and SIP Products 9
References for Telephony 10
Summary 10 References 10
Chapter 2 Internet Communications Enabied by SIP 11
Internet Multimedia Protocols 12
The Value of Signaling 13 Protocols for Media Description, Media Transport, and other
Muldmedia Delivery 14
Addressing 15 SIP in a Nutshell 15 SIP Capabilities 17 Overview of Services Provided by SIP Servers 18
Peer-to-Peer SIP (P2PSIP) 19
xü Contents
Caller Preferences 19 Mobility in the Wider Concept 20
Global Telephone Number Portability 20 SIP Application-Level Mobility 20 Context-Aware Communications: Presence and IM 21
SIP Presence 21 Instant Messaging 23 The Integration of Communications with Applications 23
E-Commerce: Customer Relations Management 23
Conferencing and Collaboration 24 Telephony Call Control Services 25 Intelligent Network Services Using SIP: ITU Services CS-1
and CS-2 25 SIP Service Creation—Telephony-Style ; ' ' 26
ENUM 27 SIP Interworking with ITU-T Protocols 27
Mixed Internet-PSTN Services 29 PSTN and INTerworking (PINT) y 29
SPIRITS * 29
TRIP 29 SIP Security 31 SIP Accessibility to Communications for the Hearing and
Speech Disabled 31 SIP Orphans 32 Commercial SIP Products 32
What SIP Does Not Do 33 Divergent Views on the Network 34
Summary .- " 35
References 35
Chapter 3 Archttectural Principles of the Internet 39
Telecom Architecture 39 Internet Architecture 42 The Internet Backbone Architecture 44
The Internet Standards Process 48 Protocols and Application Programming Interfaces 49
Is XML the Presentation Layer of the Internet Protocol
Architecture? 50 Middle-Age Symptoms of the Internet 50
Fighting Complexity 51
Summary 52 References 52
Chapter 4 DNS and ENUM 53
Introduction 53 Addressing on the Internet 54
The Universal Resource Identifier (URI) 54
Chapter 5
The Universal Resource Locator (URL) TelURI
The phone-context SIP URI
IANA ENUM Service Registrations The Domain Name System
Delegation Caching
A Partial DNS Glossary DNS and ENUM Usage Example
Finding an Outgoing SIP Server
Finding an Incoming SIP Server in the ENUM Case Call Setup Delay
DNS-Based Routing Service Using SIP SIP URI or Telephone Number? The ENUM Functional Architecture
ENUM and Number Portability Implementation Issues
DNS and SIP User Preferences
Application Scenarios for SIP Service Using ENUM PBX Enterprise Voice Network
Enterprise System with IP Communications Residential User with ENUM Service
Miscellaneous: ENUM Lookup of the Display Name DNS and Security Impersonation Eavesdropping Data Tampering Malicious Redirection Denial of Service Summary References
Real-Time Internet Multimedia
Introduction
Freshening Up on IP Multicast Protocols
Multicast Address Allocation Application-Level Multicast Transport Protocols
IP Network Layer Services Differentiated Services Resource Reservation
Integrated Services and DiffServ Networks Multiprotocol Label Switching
Media and Data Formats Media Transport Using RTP
RTP Payloads and Payload Format Specifications
55 56 56 57 58 58 59 59 60 62 63 64 67 67 67 69 71 71 72 73 74 74 76 76 77 77 77 78 78 78 79 79 81 81 83 85 85 86 86 87 88 88 89 89 90 91 92
xlv Contents
Chapter 6
Chapter 7
Multimedia Server Recording and Playback Control Session Description
Session Announcements Session Invitation
Authentication and Key Distribution Summary
References
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
User Agents Servers Location Services SIP Functions 4 Address Resolution Session-Related Functions Session Setup Media Negotiation Session Modihcation
Session Termination and Cancellation Mid-Call Signaling
Call Control
Preconditions Call Setup Nonsession-Related Functions
Mobility
Message Transport
Event Subscription and Notification Presence Publication
Authentication Challenges Extensibility
Summary References
SIP Service Creation
Services in SIP Service Example
Server Implementation
Called User Agent Implementation Calling User Agent Implementation Comparison
New Methods and Headers Service Creation Options
93 93 93 93 94 94 94 97 97 98 101 102 102 106 106 106 107 107 108 110 110 111 114 116 117 118 121 123 124 126 127 128 128 130 132 132 135 135 136 136 137 138 140 141 142
Chapter 8
Chapter 9
Chapter 10
Introduction to CPL Example of CPL Scripts SIP Common Gateway Interface
SIP Application Programming Interfaces SIP Servlets JAIN SIPandVoiceXML Summary References User Preferences Introduction Preferences of Caller Example for Contact Example for Accept-Contact Example for Reject-Contact Preferences of the Called Party
Server Support for User Preferences and for Policies Summary References SlPSecurity Threats Session Setup Presence and IM Security Mechanisms Authentication Confidentiality
Secure SIP URI Scheme Integrity Identity Media Security SRTP MIKEY SDP Security Descriptions New Directions DTLS ZRTP Summary References
-NAT and Firewall Traversal
Network Address Translators Firewalls
STUN, TURN, and ICE Application Layer Gateways Privacy Considerations 142 146 147 148 149 149 149 150 150 153 153 154 156 156 156 157 157 157 158 159 159 160 161 162 162 163 164 165 165 166 166 167 167 168 169 169 169 170 173 174 177 179 180 183
xvi Contents
Summary 184 References 184
Chapter 11 SIPTelephony 185
Basic Telephony Services 185 SIPandPSTN Interworking 185 Gateway Location and Routing 186
SIP/PSTN Protocol Interworking 187
Types of Gateways 188 SIP and Early Media 188 SIP Telephony and ISUP Tunneling 190
Enhanced Telephony Services 196 Call Control Services and Third-Party Call Control 199
Problem Statement 199 The REFER Method 201 SIP Third-Party Call Control 202
Basic Third-Party Call Control 203 Security for Third-Party Call Control 203 Peer-to-Peer Third-Party Call Control 205
Summary 206 References 207
Chapter 12 Voicemail and Universal Messaging 209
Problem Statement for Unified Messaging 209
Architecture and Operation 211 RTSP-Enabled Voice Message Retrieval 212
Depositing of Voice Messages 214 Notification for Waiting Messages 217
Simple Message Notificarion Format 217 Rieh Message Notificarion Format 220
Retrieval of Messages 221
Summary 221 References 221
Chapter 13 Presence and Instant Messaging 223
The Potential of SIP Presence, Events, and IM 224
The Evolution of IM and Presence 225 The IETF Model for Presence and IM 226 Client Server and Peer-to-Peer Presence and IM 228
SIP Event-Based Communications and Applications 229
Presence Event Package 231 Presence Information Data Format 233
The Data Model for Presence 235 Indication of Message Composition for IM 236
Rieh Presence Information 236 SIP Extensions for Instant Messaging 239
Summary 241 References 242
Chapter 14 SIP Conferendng 245
Introduction 245 SIP Conferendng Models 246
Ad Hoc and Scheduled Conferences 249 Changing the Nature of a Conference 249
Centralized Conferendng 251
Summary 251 References 251
Chapter 15 SIP Application Level Mobility 253
Mobility in Different Protocol Layers 254
Dimensions of Mobility 255 Examples of SIP Application-Layer Mobility 256
SIP Network-Based Fixed-Mobile Convergence 261 SIP Device-Based Fixed-Mobile Convergence 263 SIP Application-Layer Mobility and Mobile IP 263 Multimodal Mobile Device Technology and Issues 265
Network Control versus User Control of Mobility 266 IEEE 802.21 Media-Independent Handover (MIH) 267
Network Selecrion Issues 269
Summary 270 References 270
Chapter 16 Emergency and Preemption Communication Services 273
Requirements 274 Location Information 275
Typesof Location Information 275 Sourcesof Location Information 275 DNS-Based Location Information 275 Internet-Based Emergency Calling 277
Identifying an Internet Emergency Call: The SOS URI 278
/ Internet Emergency Call Routing 278 Security for Emergency Call Services 279 Using the PSTN for VoIP Emergency Calls 280 Emergency Communication Services 281
Emergency Call Preemption Using SIP 282 Linking SIP Preemption to IP Network and Link Layer
Preemption 284 Summary 285 References 285
Chapter 17 Accessibility for the Disabled 287
About Accessibility 287 Accessibility on Legacy Networks and on the Internet 288
Requirements for Accessibility 289
Text over IP (ToIP) 290 Performance Metrics for ToIP 293
xviü Contents Chapter 18 Chapter 19 Chapter 20 Transcoding Services Transcoding Scenarios
Call Control Models for Transcoding Services Summary
References
Quality of Service for Real-Time Internet Communications
Voice Quality Metrics Delay Limits for Voice Burst vs. Average Packet Loss Acoustics and the Network Internet Codecs
Codecs in Wireless Networks and Transcoding Codec Bandwidth
The Endpoint Quality for Voice The Internet Performance
Concerns Regarding Congestion Control Internet Traffic Statistics: Voice Is Negligible
A Summary of Internet QoS Technologies # Best Effort Is for the Best Reasons
Monitoring QoS for Real-Time Communications Summary
References
SIP Component Services
Master/SIave VoIP Systems IP Telephony Gateways
The Converged Applications Environment The Control of Service Context
Voicemail
Collecting DTMF Digits
Interactive Voice Response System Scheduled Conference Service Summary
References
Peer-to-Peer SIP
Definitions for P2P Networks , Overlay Networks
Peer-to-Peer Networks
Distributed Hash Tables (DHTs) Characteristics of P2P Computing Security of P2P Networks
The Chord Protocol P2P SIP CS SIP Model P2P SIP Model 294 294 296 298 299 301 303 303 304 304 305 307 307 308 308 309 309 311 313 314 315 315 317 318 320 323 326 328 330 333 335 337 337 339 340 340 341 342 344 344 345 346 347 348
Use Cases for P2P SIP 348 Disruption of the VoIP Infrastructure Model 349
Summary 350 References 351
Chapter 21 Conclusions and Future Directions 353
Short Term Challenges 355 Future Services: The Internet Is the Service 355
Still to Develop: Peer-to-Peer SIP Standards 355
Prediction: The Long Road Ahead 356
Summary 356 References 356
Index 357
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