VoIP Emergency Calling: Foundations and Practice

Foreword ix

Useful Links xi

List of Abbreviations xiii

1 Introduction 1

1.1 Calling over the Internet 2

1.2 VoIP Emergency Calling Problem Statement 2

1.3 Emergency Communication 5

1.4 Overview of this Book 6

References 7

2 Emergency Calling 9

2.1 Overview 9

2.2 Infrastructure Requirements 10

2.3 The Role of Location Information 12

References 16

3 The ECRIT Emergency Calling Architecture 19

3.1 Overview 20

3.2 Location Information 22

3.2.1 PIDF-LO 23

3.2.2 Location by Value and Location by Reference 30

3.2.3 Location Conveyance 33

3.3 Service URNs 39

3.4 Determining the Appropriate PSAP – the LoST Protocol 40

3.4.1 The Mapping Process – findService 41

3.4.2 Retrieving the Service List – listServicesByLocation 44

3.4.3 Address Validation 46

3.4.4 Areas of Responsibility – serviceBoundary 47

3.4.5 LoST Server Discovery 49

3.4.6 LoST Architecture 50

3.4.7 Private and Public LoST Trees 53

3.4.8 LoST Synchronization 54

3.5 The Emergency Call Itself 57

3.5.1 Initiating Emergency Calls 58

3.5.2 Routing Emergency Calls 60

3.5.3 Assembling the SIP INVITE Message 61

3.6 Home Dial String Configuration via LoST 62

3.7 Deployment Models 66

3.8 Considerations for Proxies 69

3.9 Standardization 71

3.10 Summary 73

References 74

4 Including Location Information 77

4.1 Location Configuration 78

4.1.1 HTTP Enabled Location Delivery (HELD) 78

4.1.2 DHCP Options for Location Configuration 84

4.1.3 LLDP-MED 86

4.1.4 Protocol Comparison 88

4.1.5 Conversion between Location Formats 88

4.2 Positioning Using GPS 90

4.3 Network-Based Positioning 91

4.4 Location Hiding 92

4.5 Default Location 94

References 94

5 Implementation and Regulatory Considerations 97

5.1 Distribution of Implementation Tasks 98

5.1.1 Emergency Call Centers (PSAPs) 98

5.1.2 VoIP Software and Hardware Manufacturers 99

5.1.3 Network Operators and ISPs 100

5.1.4 VoIP Operators 101

5.1.5 PSTN Operators 102

5.1.6 Unassigned Responsibilities 102

5.1.7 Summary 103

5.2 Austria 103

5.2.1 The Telecommunications Act 104

5.2.2 KEM-V 104

5.2.3 RTR Guidelines for VoIP Operators 105

5.2.4 AK-TK Recommendations 106

5.2.5 Emergency Calling in Austria 107

5.3 The United States 112

5.3.1 9-1-1 Regulation 113

5.3.2 9-1-1 History 116

5.3.3 Automatic Location Information 120

5.4 The European Union 122

5.5 Japan 123

5.5.1 Regulatory Framework 123

5.5.2 Call Handling 126

5.5.3 Location Information and Privacy 127

5.6 Summary 129

References 130

6 VoIP Emergency Calling in Practice 133

6.1 Software 133

6.1.1 HELD Clients and Servers 134

6.1.2 DHCP Location Encoders and Decoders 137

6.1.3 Wireshark for DHCP Location 139

6.1.4 OpenLLDP 139

6.1.5 HELD Support in Firefox 140

6.1.6 LoST Implementations 141

6.1.7 Zap! with Emergency Calling Extensions 142

6.1.8 Ecritdroid 145

6.1.9 EcritXUL 147

6.1.10 Multi-Part Body Extension to Asterisk 149

6.1.11 IMS Core Emergency Services 150

6.2 Practice Exercises 151

6.2.1 Location Configuration: DHCPv4 with Civic Addresses 152

6.2.2 Location Configuration: Simulating a HELD Server 155

6.2.3 Location Configuration: Location-Enabling a Network with HELD 156

6.2.4 Mapping: Querying the LoST Server 160

6.2.5 SIP Calling: Call Setup with Location Configuration 162

6.2.6 ECRIT Calling: A Complete System 166

References 170

7 Security 171

7.1 ECRIT Security 172

7.1.1 Determining the Caller’s Location 172

7.1.2 Determining the Proper PSAP 175

7.1.3 Delivering the Call 175

7.1.4 Considerations for Proxies 176

7.2 Location Security 177

7.2.1 Location Privacy 178

7.2.2 Location Assurance 182

7.2.3 Location Protection 184

7.3 PSAP and VoIP Network Security 186

7.3.1 Basic PSAP Protection Measures 187

7.3.2 PSAP Fraud Mitigation 188

7.3.3 VoIP Provider Call Validation 192

References 195

8 Ongoing Emergency Calling Work 197

8.1 Prototyping, Implementation, and Interoperability 198

8.2 Ongoing Standardization Issues 200

8.2.1 Default PSAPs 200

8.2.2 Unauthenticated Emergency Calls 200

8.2.3 VPN Problems 201

8.2.4 Home Emergency Dial String Issues 201

8.2.5 Updating the List of Available Emergency Services – the LoST Service List Boundary 202

8.2.6 Order of Location Configuration 204

8.2.7 Notifying Users of Emergency Calls 205

8.2.8 Connecting Emergency Dial Strings and Emergency Authorities 205

8.2.9 Disconnection during an Emergency Call 206

8.2.10 LLDP-MED ELIN will not be Supported 206

8.2.11 Civic Boundaries 206

8.2.12 LoST Service Boundary References and Location Types 207

8.2.13 Emergency Calls to Counseling Services 208

8.3 Ongoing Implementation Issues 209

8.3.1 Service URNs as Request URIs 209

8.3.2 Converting from the DHCP Location Format to PIDF-LO 209

8.3.3 LLDP-MED Difficulties 210

8.3.4 Multi-Part SIP Bodies and Message Size 210

References 211

9 Summary and the Outlook for the Future 213

Index 217