IP Telephony Cookbook

Final deliverable


Table of Contents

1. Introduction
1.1. Goal
1.2. Reasons for writing this document
1.3. Contents
1.4. How to read this document
1.5. Techno-economic aspect of moving from classic telephony to VoIP
2. Technology Background
2.1. Components
2.1.1. Terminal
2.1.2. Server
2.1.3. Gateway
2.1.4. Conference Bridge
2.1.5. Addressing
2.2. Protocols
2.2.1. H.323
2.2.2. SIP
2.2.3. Media Gateway Control Protocols
2.2.4. Proprietary Signaling Protocols
2.2.5. Real Time Protocol (RTP) and Real Time Control Protocol (RTCP)
3. IP Telephony Scenarios
3.1. Introduction
3.2. Scenario 1: Long-distance least cost routing
3.2.1. Least Cost Routing - An implementation example
3.3. Scenario 2: Alternatives to legacy PBX systems
3.3.1. Scenario 2a: IP-Phones without a PBX system
3.3.2. Scenario 2b: Integration of VoIP with legacy PBX systems
3.3.3. Scenario 2c: Full replacement of legacy PBX systems
3.4. Scenario 3: Integration of VoIP and Videoconferencing
3.4.1. Integrating Voice and Videoconferencing over IP - an example
4. Setting up basic services
4.1. General concepts
4.1.1. Architecture
4.1.2. Robustness
4.1.3. Management issues
4.2. Dialplans
4.3. Authentication
4.3.1. Authentication in H.323
4.3.2. Authentication in SIP
4.4. Examples
4.4.1. Example 1: Simple, use IP telephony like legacy telephony
4.4.2. Example 2: Complex, full featured
4.5. Setting up H.323 services
4.5.1. Using a Cisco Multimedia Conference Manager (MCM gatekeeper)
4.5.2. Using a Radvision Enhanced Communication Server (ECS gatekeeper)
4.5.3. Using an OpenH323 Gatekeeper - GNU Gatekeeper
4.6. Setting up SIP services
4.6.1. Operation of SIP Servers
4.6.2. SIP Express Router
4.6.3. Asterisk
4.6.4. VOCAL
4.7. Firewalls and NAT
4.7.1. Firewalls and IP telephony
4.7.2. NAT and IP telephony
4.7.3. SIP and NAT
5. Setting up Advanced Services
5.1. Gatewaying
5.1.1. Gateway interfaces
5.1.2. Gatewaying from H.323 to PSTN/ISDN
5.1.3. Gatewaying from SIP to PSTN/ISDN
5.1.4. Gatewaying from SIP to H.323 and vice versa
5.1.5. Accounting Gateways
5.2. Supplementary services
5.2.1. Supplementary Services using H.323
5.2.2. Supplementary Services using SIP
5.3. Multipoint Conferencing
6. Setting up Value-Added Services
6.1. Web Integration of H.323 services
6.1.1. RADIUS-based methods
6.1.2. SNMP-based methods
6.1.3. Cisco MCM GK API
6.1.4. GNU GK Status Interface
6.2. Web Integration of SIP Services
6.2.1. Click-to-Dial
6.2.2. Presence
6.2.3. Missed Calls
6.2.4. Serweb
6.2.5. SIP Express Router Message Store
6.3. Voicemail
7. Global telephony integration
7.1. Technology
7.1.1. H.323 LRQ
7.1.2. H.225.0 Annex G
7.1.3. Telephony Routing Over IP (TRIP)
7.1.4. SRV-Records
7.1.5. ENUM
7.2. Call routing today
7.2.1. SIP
7.2.2. Using H.323
7.3. Utopia: Setting up global IP telephony
7.4. Towards Utopia
7.4.1. Call Routing Assistant
8. Regulatory / Legal considerations
8.1. Overall
8.2. What does regulation mean for Voice over IP?
8.3. Regulation of Voice over IP in the European Union
8.3.1. Looking back into Europe's recent history in regulation
8.3.2. The New Regulatory Framework - Technological Neutrality
8.3.3. New Regulatory Framework - an overview
8.3.4. Authorization System instead of Licensing System
8.3.5. Numbering
8.3.6. Access
8.3.7. Interconnection
8.3.8. Quality of Service
8.4. Voice over IP in the United States
8.5. Conclusion and Summary
A. European IP Telephony Projects
A.1. Evolute
A.2. 6Net
A.3. Eurescom P1111 (Next-Gen open Service Solutions over IP (N-GOSSIP)
A.4. HITEC
A.5. The GRNET/RTS project
A.6. SURFWorks
A.7. VC Stroom
A.8. Voice services in the CESNET2 network
B. IP Telephony Hardware/Software
B.1. Softphones
B.2. Hardphones
B.3. Servers
B.4. Gateways
B.5. Testing
B.6. Miscellaneous
Glossary

List of Figures

2.1. Scope and Components defined in H.323
2.2. H.323 protocol architecture
2.3. Discovery and registration process
2.4. Direct signaling model
2.5. Gatekeeper Routed call signaling model
2.6. Gatekeeper Routed H.245 control model
2.7. OPENLOGICALCHANNELACK message content
2.8. Supplementary services of the H.450-Series
2.9. External address resolution using LRQs
2.10. Sample H.323 Call Setup Scenario
2.11. UAC and UAS
2.12. Session Invitation
2.13. Registrar Overview
2.14. SIP Redirection
2.15. SIP Transactions
2.16. SIP Dialog
2.17. SIP Trapezoid
2.18. REGISTER Message Flow
2.19. INVITE Message Flow
2.20. BYE Message Flow (With and without Record Routing)
2.21. Event Subscription And Notification
2.22. Instant Messages
2.23. Application Scenario for Media Gateway Control Protocols
2.24. RTP Header
3.1. Traditional separation of data and telephony between locations
3.2. Integration of data and telephony between locations
3.3. Least cost routing architecture
3.4. Legacy PBX which trunks to the PSTN
3.5. IP-Phone to IP-Phone without PBX
3.6. Integration of IP-Telephony with legacy PBX system
3.7. IP-Telephony fully replacing PBX
3.8. Integrated Voice and Video over IP architecture at SURFnet offices
4.1. SIP/H.323 zone using a multiprotocol server
4.2. SIP/H.323 zone using a signaling gateway
4.3. Routing based on number prefix
4.4. Per number routing
4.5. Per number routing with a) two or b) one gateways
4.6. Prefix based trunking
4.7. Static individual trunking
4.8. Dynamic individual trunking
4.9. REGISTER Message Flow
4.10. INVITE with authentication
4.11. Simple IP telephony example.
4.12. Example of a multi-server IP telephony zone
4.13. Gatekeeper features examples
4.14. ECS local administration entry
4.15. ECS administration menus
5.1. Voice gateway interfaces - PBX role
5.2. E&M signalling, type V
5.3. ISDN configuration
5.4. Q.931 call control messages in call-setup with the en-bloc signal
5.5. Q.931 call control messages in call-setup with overlap
5.6. OnLan configuration entry
5.7. OnLan Unit Identification
5.8. OnLan Miscellaneous Parameters and gateway registration on gatekeeper
5.9. OnLan defined gateway services
5.10. OnLan editing of a service definition
5.11. CISCO voice gateway interconnection
5.12. SIP / H.323 gateway containing SIP proxy and registrar
5.13. SIP / H.323 gateway containing a H.323 gatekeeper
5.14. SIP / H.323 gateway independent
5.15. Messages exchanged to implement the CT-SS without Gatekeeper
5.16. Example of Call Transfer Supplementary Service without Gatekeeper - Ohphone modified interface
5.17. Messages exchange for Gatekeeper managed CT-SS
5.18. On-hold Call Flow
5.19. Call Transfer Call Flow
5.20. CPL Editor
5.21. MCU function in Gatekeeper
6.1. REFER Based Click-to-Dial
6.2. Serweb - My Account
6.3. Serweb - Phonebook
6.4. Serweb - Missed Calls
6.5. Serweb - Message Store
6.6. Voicemail
7.1. Location Request mechanism
7.2. Usage of H.225.0 Annex G
7.3. TRIP location servers and their initial data.
7.4. TRIP: LS tell peers their initial data
7.5. TRIP: Advertising gathered knowledge
7.6. TRIP: Route aggregation
7.7. Using peers to route external calls.
7.8. Gatekeeper hierarchy
7.9. Usage of a Call Routing Assistant
A.1. CESNET IP Telephony Network