VoIP and Unified Communications: Internet Telephony and the Future Voice Network

by William A. Flanagan

Overview

Translates technical jargon into practical business communications solutions

This book takes readers from traditional voice, fax, video, and data services delivered via separate platforms to a single, unified platform delivering all of these services seamlessly via the Internet. With its clear, jargon-free explanations, the author enables all readers to better understand and assess the growing number of voice over Internet protocol (VoIP) and unified communications (UC) products and services that are available for businesses.

VoIP and Unified Communications is based on the author's careful review and synthesis of more than 7,000 pages of published standards as well as a broad range of datasheets, websites, white papers, and webinars. It begins with an introduction to IP technology and then covers such topics as:

• Packet transmission and switching
• VoIP signaling and call processing
• How VoIP and UC are defining the future
• Interconnections with global services
• Network management for VoIP and UC

This book features a complete chapter dedicated to cost analyses and payback calculations, enabling readers to accurately determine the short- and long-term financial impact of migrating to various VoIP and UC products and services. There's also a chapter detailing major IP systems hardware and software. Throughout the book, diagrams illustrate how various VoIP and UC components and systems work. In addition, the author highlights potential problems and threats to UC services, steering readers away from common pitfalls.

Concise and to the point, this text enables readers—from novices to experienced engineers and technical managers—to understand how VoIP and UC really work so that everyone can confidently deal with network engineers, data center gurus, and top management.

Product Details

ISBN-13:	9781118166031
Publisher:	Wiley
Publication date:	02/27/2012
Sold by:	JOHN WILEY & SONS
Format:	eBook
Pages:	320
File size:	8 MB

About the Author

WILLIAM A. FLANAGAN is President and founder of Flanagan Consulting. With three decades of telecommunications experience, Mr. Flanagan is an expert in voice and data technologies, products, markets, and customers. His network designs have solved problems for enterprises, government agencies, and carriers.

Table of Contents

Preface xiii

Acknowledgments xv

1 IP Technology Disrupts Voice Telephony 1

1.1 Introduction to the Public Switched Telephone Network / 1

1.2 The Digital PSTN / 2

1.3 The Packet Revolution in Telephony / 8

1.3.1 Summary of Packet Switching / 9

1.3.2 Link Capacity: TDM versus Packets / 11

1.3.3 VoIP and “The Cloud” / 13

IN SHORT: Reading Network Drawings / 14

2 Traditional Telephones Still Set Expectations 17

2.1 Availability: How the Bell System Ensured Service / 18

2.2 Call Completion / 19

2.3 Sound Quality: Encoding for Recognizable Voices / 20

2.4 Low Latency / 23

2.5 Call Setup Delays / 24

2.6 Impairments Controlled: Echo, Singing, Distortion, Noise / 25

3 From Circuits to Packets 27

3.1 Data and Signaling Preceded Voice / 27

3.1.1 X.25 Packet Data Service / 27

3.1.2 SS7: PSTN Signaling on Packets / 28

3.1.3 ISDN / 29

3.2 Putting Voice into Packets / 30

3.2.1 Voice Encoding / 31

3.2.2 Dicing and Splicing Voice Streams / 32

3.2.3 The Latency Budget / 33

4 Packet Transmission and Switching 37

4.1 The Physical Layer: Transmission / 39

IN SHORT: The Endian Wars / 40

4.2 Data Link Protocols / 41

4.3 IP, the Network Protocol / 43

4.4 Layer 4 Transport Protocols / 47

4.4.1 Transmission Control Protocol / 47

4.4.2 User Datagram Protocol / 50

4.4.3 Stream Control Transmission Protocol / 51

4.5 Higher Layer Processes / 54

4.5.1 RTP / 54

4.5.2 RTCP / 57

4.5.3 Multiplexing RTP and RTCP on One UDP Port / 58

4.5.4 RTP Mixers and Translators / 59

4.5.5 Layered Encoding / 60

4.5.6 Profiles for Audio and Video Conferences / 60

4.5.7 Security via Encryption / 61

IN SHORT: Public Key Infrastructure (PKI) / 62

4.6 Saving Bandwidth / 64

4.6.1 Voice Compression / 64

4.6.2 Header Compression / 66

4.6.3 Silence Suppression, VAD / 67

4.6.4 Sub-Packet Multiplexing / 69

4.6.5 Protocol and Codec Selection / 70

4.7 Differences: Circuit versus Packet Switched / 71

4.7.1 Power to the Desktop Phone / 71

4.7.2 Phone as Computer and Computer as Phone / 72

4.7.3 Length of a Phone Line / 72

4.7.4 Scaling to Large Size / 75

4.7.5 Software Ownership and Licenses / 75

5 VoIP Signaling and Call Processing 77

5.1 What Packet Voice and UC Systems Share / 78

5.2 Session Initiation Protocol (SIP) / 80

5.2.1 SIP Architecture / 81

5.2.2 SIP Messages / 88

5.2.3 SIP Header Fields and Behaviors / 94

5.3 Session Description Protocol / 101

IN SHORT: ABNF / 104

5.4 Media Gateway Control Protocol / 107

5.4.1 MGW Functions / 107

5.4.2 MGW Connection Model / 110

5.4.3 Megaco Procedures / 112

5.4.4 Megaco Details / 115

5.4.5 Signaling Conversion / 119

5.4.6 Voice Transcoding / 119

5.5 H.323 / 120

5.5.1 H.323 Architecture / 121

5.5.2 Gatekeeper / 123

5.5.3 Gateway / 126

5.5.4 Terminal / 126

5.5.5 Multipoint Control Unit / 127

5.5.6 Call Procedures / 128

5.6 Directory Services / 134

5.6.1 Domain Name Service (DNS) / 134

5.6.2 ENUM / 135

6 VoIP and Unified Communications Define the Future 139

6.1 Voice as Before, with Additions / 139

6.2 Legacy Services to Keep and Improve with VoIP / 140

6.2.1 Flexible Call Routing and 800 Numbers / 141

6.2.2 Call on Hold / 141

6.2.3 Call Transfer / 142

6.2.4 Call Forwarding / 142

6.2.5 Audio Conferencing / 142

6.2.6 Video Conferencing / 143

6.2.7 Local Number Portability / 144

6.2.8 Direct Inward Dialing, Dialed Number Indication / 144

6.2.9 Call/Message Waiting / 145

6.2.10 Call Recording / 146

6.2.11 Emergency Calling (E911) / 146

6.2.12 Tracking IP Phone Locations for E911 / 150

6.3 Facsimile Transmission / 153

6.3.1 Facsimile on the PSTN / 153

6.3.2 Real-Time Fax over IP: Fax Relay or T.38 / 155

6.3.3 Store-and-Forward Fax Handling / 160

6.3.4 IP Faxing over the PSTN / 161

6.4 Phone Features Added with VoIP/UC / 162

6.4.1 Presence / 163

6.4.2 Forking / 163

6.4.3 Voicemail¼eMail / 163

6.4.4 SMS Integration / 164

6.4.5 Instant Messaging / 165

6.4.6 Webinar Broadcasts / 168

6.4.7 Telepresence / 168

6.4.8 More UC Features to Consider / 168

7 How VoIP and UC Impact the Network 171

7.1 Space, Power, and Cooling / 171

7.2 Priority for Voice, Video, Fax Packets / 172

7.3 Packets per Second / 174

7.4 Bandwidth / 174

7.5 Security Issues / 175

7.5.1 Eavesdropping and vLAN Hopping / 176

7.5.2 Access Controls for Users and Connections / 176

7.5.3 Modems / 177

7.5.4 DNS Cache Poisoning / 177

IN SHORT: Earliest Instance of DNS Cache Poisoning / 179

7.5.5 Toll Fraud / 179

7.5.6 Pay-per-Call Scams / 179

7.5.7 Vishing / 180

7.5.8 SIP Scanning/SPIT / 180

7.5.9 Opening the Firewall to Incoming Voice / 181

7.6 First Migration Steps While Keeping Legacy Equipment / 181

7.6.1 Circuit-Switched PBX / 182

7.6.2 Digital Phones / 182

7.6.3 Analog Phones and FX Service / 183

7.6.4 Facsimile Machines / 184

7.6.5 Modems / 185

8 Interconnections to Global Services 187

8.1 Media Gateways / 188

8.2 SIP Trunking / 192

8.3 Operating VoIP Across Network Address Translation / 196

8.3.1 Failures of SIP, SDP (Signaling) / 199

8.3.2 Failures of RTP (Media) / 199

8.3.3 Solutions / 200

8.3.4 STUN: Session Traversal Utilities for NAT / 201

8.3.5 TURN: Traversal Using Relays around NAT / 204

8.3.6 ICE: Interactive Connectivity Establishment / 206

8.4 Session Border Controller / 207

8.4.1 Enterprise SBC / 209

8.4.2 Carrier SBC / 210

8.5 Supporting Multiple-Carrier Connections / 212

8.6 Mobility and Wireless Access / 213

8.6.1 VoIP on Wireless LANs/Wi-Fi / 213

8.6.2 Integration of Wi-Fi and Cellular Services / 214

8.6.3 Packet Voice on Mobile Broadband: WiMAX, LTE / 214

8.6.4 Radio over VoIP / 215

IN SHORT: E&M Voice Signaling / 216

9 Network Management for VoIP and UC 217

9.1 Starting Right / 218

9.1.1 Acceptance Testing / 219

9.1.2 Configuration Management and Governance / 220

9.1.3 Privilege Setting / 220

9.2 Continuous Monitoring and Management / 221

9.2.1 NMS Software / 222

9.2.2 Simple Network Management Protocol / 223

9.2.3 Web Interface / 224

9.2.4 Server Logging / 224

9.2.5 Software Maintenance / 225

9.2.6 Quality of Service/Experience Monitoring / 225

9.2.7 Validate Adjustments and Optimization / 226

9.3 Troubleshooting and Repair / 226

9.3.1 Methods / 226

9.3.2 Software Tools / 228

9.3.3 Test Instruments / 229

10 Cost Analysis and Payback Calculation 231

11 Examples of Hardware and Software 237

11.1 IP Phones / 237

11.2 Gateways / 240

11.3 Session Border Controllers / 242

11.4 Call-Switching Servers / 244

11.4.1 IP PBX / 246

11.4.2 Conference Bridges/Controllers / 248

11.4.3 Call Recorder / 250

11.5 Hosted VoIP/UC Service / 251

11.6 Management Systems/Workstations / 252

12 Appendixes 253

12.1 Acronyms and Definitions / 253

12.2 Reference Documents / 268

12.2.1 RFCs / 268

12.2.2 ITU Recommendations / 272

12.2.3 Other Sources / 272

12.3 Message and Error Codes / 274

Index 277