Switching to VoIP

vii

Table of Contents

Foreword

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

xiii

Preface

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

xv

1. Voice and Data: Two Separate Worlds?

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1

The PSTN 2

Key Systems and PBXs 4

Limits of Traditional Telephony 5

VoIP in the Home 9

VoIP in Business 9

VoIP’s Changing Reputation 9

Key Issues: Voice and Data: Two Separate Worlds 10

2. Voice over Data: Many Conversations, One Network

. . . . . . . . . . . . . . . . . . . .

12

VoIP or IP Telephony 13

Distributed Versus Mainframe 27

Key Issues: Voice over Data: Many Conversations, One Network 32

3. Linux as a PBX

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

34

Free Telephony Software 34

Installing Legacy Interface Cards 37

Compiling and Installing Asterisk 41

Monitoring Asterisk 54

Key Issues: Linux as a PBX 57

4. Circuit-Switched Telephony

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

59

Regulation and Organization of the PSTN 59

Components of the PSTN 62

viii | Table of Contents

Customer Premises ...