Voice over IP Fundamentals, Second Edition By Jonathan Davidson, James Peters, Manoj Bhatia, Satish Kalidindi, Sudipto Mukherjee Publisher: Cisco Press Pub Date: July 27, 2006 Print ISBN-10: 1-58705-257-1 Print ISBN-13: 978-1-58705-257-6 Pages: 432 Table of Contents | Index A systematic approach to understanding the basics of voice over IP Understand the basics of enterprise and public telephony networking, IP networking, and how voice is transported over IP networks Learn the various caveats of converging voice and data networks Examine the basic VoIP signaling protocols (H.323, MGCP/H.248, SIP) and primary legacy voice signaling protocols (ISDN, C7/SS7) Explore how VoIP can run the same applications as the existing telephony system but in a more cost-efficient and scalable manner Delve into such VoIP topics as jitter, latency, packet loss, codecs, QoS tools, and security Voice over IP (VoIP) has become an important factor in network communications, promising lower operational costs, greater flexibility, and a variety of enhanced applications To help you understand VoIP networks, Voice over IP Fundamentals provides a thorough introduction to the basics of VoIP Voice over IP Fundamentals explains how a basic IP telephony infrastructure is built and works today, major concepts concerning voice and data networking, and transmission of voice over data networks You'll learn how voice is signaled through legacy telephone networks, how IP signaling protocols are used to interoperate with current telephony systems, and how to ensure good voice quality using quality of service (QoS) Even though Voice over IP Fundamentals is written for anyone seeking to understand how to use IP to transport voice, its target audience comprises both voice and data networking professionals In the past, professionals working in voice and data networking did not have to understand each other's roles However, in this world of time-division multiplexing (TDM) and IP convergence, it is important to understand how these technologies work together Voice over IP Fundamentals explains all the details so that voice experts can understand data networking and data experts can understand voice networking The second edition of this best-selling book includes new chapters on the importance of billing and mediation in a VoIP network, security, and the common types of threats inherent when packet voice environments, public switched telephone networks (PSTN), and VoIP interoperate It also explains enterprise and service-provider applications and services Voice over IP Fundamentals, Second Edition By Jonathan Davidson, James Peters, Manoj Bhatia, Satish Kalidindi, Sudipto Mukherjee Publisher: Cisco Press Pub Date: July 27, 2006 Print ISBN-10: 1-58705-257-1 Print ISBN-13: 978-1-58705-257-6 Pages: 432 Table of Contents | Index Copyright About the Authors About the Technical Reviewers Acknowledgments Icons Used in This Book Introduction Purpose of This Book Who Should Read This Book? Chapter Organization Features and Text Conventions Timeliness The Road Ahead Part I: PSTN Chapter 1 Overview of the PSTN and Comparisons to Voice over IP The Beginning of the PSTN Understanding PSTN Basics PSTN Services and Applications Drivers Behind the Convergence Between Voice and Data Networking Packet Telephony Network Drivers New PSTN Network Infrastructure Model Summary Chapter 2 Enterprise Telephony Today Similarities Between PSTN and ET Differences Between PSTN and ET Common ET and PSTN Interworking Summary Chapter 3 Basic Telephony Signaling Signaling Overview E&M Signaling CAS ISDN QSIG DPNSS Summary Chapter 4 Signaling System 7 SS7 Network Architecture SS7 Protocol Overview SS7 Examples List of SS7 Specifications Summary Chapter 5 PSTN Services Plain Old Telephone Service Service Provider Services Summary Part II: Voice over IP Technology Chapter 6 IP Tutorial OSI Reference Model Internet Protocol Data Link Layer Addresses IP Addressing Routing Protocols EIGRP IP Transport Mechanisms Summary References Chapter 7 VoIP: An In-Depth Analysis Delay/Latency Jitter Pulse Code Modulation Voice Compression Echo Packet Loss Voice Activity Detection Digital-to-Analog Conversion Tandem Encoding Transport Protocols Dial-Plan Design End Office Switch Call-Flow Versus IP Phone Call Summary References Chapter 8 Quality of Service QoS Network Toolkit Edge Functions Traffic Policing Backbone Networks Rules of Thumb for QoS Cisco Labs' QoS Testing Summary Chapter 9 Billing and Mediation Services Billing Basics Case Study: Cisco SIP Proxy Server and Billing Challenges for VoIP Networks Mediation Services Summary Chapter 10 Voice Security Security Requirements Security Technologies Protecting Voice Devices Protecting IP Network Infrastructure Security Planning and Policies Summary Part III: IP Signaling Protocols Chapter 11 H.323 H.323 Elements H.323 Protocol Suite H.323 Call-Flows Summary Chapter 12 SIP SIP Overview SIP Message Building Blocks Basic Operation of SIP SIP Procedures for Registration and Routing SIP Extensions Summary Chapter 13 Gateway Control Protocols MGCP Overview MGCP Model MGCP Commands and Messages MGCP Call Flows Advanced MGCP Features H.248/MEGACO Summary Part IV: VoIP Applications and Services Chapter 14 PSTN and VoIP Interworking Cisco Packet Telephony Packet Voice Network Overview PGW2200 Architecture and Operations PGW2200 Implementation PSTN Signaling Over IP Changing Landscape of PSTN-IP Interworking Session Border Controller (SBC) Summary Chapter 15 Service Provider VoIP Applications and Services The Service Provider Dilemma Service Provider Applications and Benefits Service Provider VoIP Deployment: Vonage Service Provider Case Study: Prepaid Calling Card Session Border Control: Value Addition VoIP Peering: Top Priority for the Service Providers Service Provider VoIP and Consumer Fixed Mobile Convergence Summary Chapter 16 Enterprise Voice over IP Applications and Services Migrating to VoIP Architecture Enterprise Voice Applications and Benefits Advanced Enterprise Applications Wi-FiEnabled Phones Better Voice Quality Using Wideband Codecs Summary Index Copyright Jonathan Davidson, James Peters, Manoj Bhatia, Satish Kalidindi, and Sudipto Mukherjee Copyright© 2007 Cisco Systems, Inc Published by: Cisco Press 800 East 96th Street Indianapolis, IN 46240 USA All rights reserved No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without written permission from the publisher, except for the inclusion of brief quotations in a review Printed in the United States of America 1 2 3 4 5 6 7 8 9 0 First Printing July 2006 Library of Congress Cataloging-in-Publication Number: 2005934132 Warning and Disclaimer This book is designed to provide information about the fundamentals of Voice over IP (VoIP) Every effort has been made to make this book as complete and as accurate as possible, but no warranty or fitness is implied The information is provided on an "as is" basis The authors, Cisco Press, and Cisco Systems, Inc shall have neither liability nor responsibility to any person or entity with respect to any loss or damages arising from the information contained in this book or from the use of the discs or programs that may accompany it The opinions expressed in this book belong to the author and are not necessarily those of Cisco Systems, Inc Feedback Information At Cisco Press, our goal is to create in-depth technical books of the highest quality and value Each book is crafted with care and precision, undergoing rigorous development that involves the unique expertise of members from the professional technical community Readers' feedback is a natural continuation of this process If you have any comments regarding how we could improve the quality of this book, or otherwise alter it to better suit your needs, you can contact us through email at feedback@ciscopress.com Please make sure to include the book title and ISBN in your message We greatly appreciate your assistance Trademark Acknowledgments All terms mentioned in this book that are known to be trademarks or service marks have been appropriately capitalized Cisco Press or Cisco Systems, Inc., cannot attest to the accuracy of this information Use of a term in this book should not be regarded as affecting the validity of any trademark or service mark Publisher Paul Boger Cisco Representative Anthony Wolfenden Cisco Press Program Jeff Brady Manager Acquisitions Editor Elizabeth Peterson Production Manager Patrick Kanouse Senior Development Christopher A Cleveland Editor Project Editor Tonya Simpson Copy Editor Karen Gill Technical Editors Brian Gracely, Jesse Herrera, Brion Washington Editorial Assistant Vanessa Evans Book Designer Louisa Adair Cover Designer Louisa Adair Composition Mark Shirar Indexer Tim Wright Corporate Headquarters example of redirect servers, example of registration procedure state changes during requests handling preferences, specifying REFER structure of responses final structure of RFC 3841, caller/callee preferences signaling, supported transport layer protocols transactions user mobility SIP-T SIPO (Status Indicator Processor Outage) sliding windows SLT (Signaling Link Terminal) SMH (Signaling Message Handling) SN (Subsriber Number) SNA (Systems Network Architecture) 2nd SNM (Signaling Network Management) changeover/changeback congestion control message structure rerouting soft phones 2nd softswitches PSTN signaling over IP Source address field (IP packets) source codecs specifications FR.12 ITU-T, H.323 SS7 specifying SIP request handling preferences speed dialing, POTS SPF (shortest path first) algorithm SPs (service providers) business services call centers Centrex Virtual Private Voice Networks database services operator services POTS CLASS features custom calling features features voice mail SRTP (Secure Real-time Transport Protocol) SS6 SS7 (Signaling System 7) A-links ACM ANM associated signaling C-links combined linksets CSS7 D-links databases E-links examples 800 queries basic call setup and teardown F-links fully associated global title translation ISUP call control messages call setup and teardown end-to-end signaling message format services message structure MNM interfaces SP requirements MTP data layer network layer physical layer nonassociated signaling point code protocol stack quasi-associated signaling RELEASE message retransmission messages SCCP SCPs signaling links performance signaling traffic termination specifications SSP STP global title translation hierarchical structure TCAP TUP SSPs (Service Switching Points) standards, G-series recommendations standards-based packet infrastructure states of presence static jitter buffers Status field (LSSUs) Status Indicator Processor Outage (SIPO) status information (RAS), obtaining STP (Switching Transfer Point) STPs (Signal Transfer Points) A-links global title translation hierarchical structure streams, RTP structure of SIP requests/responses subinterfaces (Frame Relay), GTS configuration subjective voice testing subnets broadcast packets SUBSCRIBE method (SIP) subscriber loop Subscriber Number (SN) supervision signaling Bell System MF digital trunks CCITT No 5 method R2 analog trunks digital trunks Single Frequency signaling supplementary services ISDN ISUP Supported header (SIP) supported protocols on PGW2200 Switch-Computer Applications Interface (SCAI) switches 2nd Class 5 dedicated circuits end office hierarchical structure tandem trunks System Control Unit (H.323) Systems Network Architecture (SNA) 2nd Index [SYMBOL] [A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [K] [L] [M] [N] [O] [P] [Q] [R] [S] [T] [U] [V] [W] [X] [Z] T reference point (QSIG) T1 lines 23B+D framing format T1 links tail-drops tandem switches 2nd 3rd tandem-compression TASI (Time Assignment Speech Interpolation) TCAP (Transaction Capabilities Applications Part) 2nd 3rd TCP (Transmission Control Protocol) 2nd TCP header compression TCP intercept TCP/IP toll-bypass TDM (time-division multiplexing) telephony networks business services call centers Centrex four-telephone networks line noise meshed, scalability phone lines POTS PSTN, history of ring-down circuits signaling SPs database services operator services terminals, H.323 testing QoS tools voice quality TFA messages (Transfer Allowed) third-party application development tools for PGW2200 three-way calling POTS throttling, BECN-based tie-lines 2nd Time Assignment Speech Interpolation (TASI) Time To Live fields (IP packets) time-division multiplexing (TDM) timestamping RTP TLS (Transport Layer Security) toggling BIB/FIB values toll operators toll-bypass 2nd tones (in-band signaling) tools cRTP QoS lab testing total delay, comparing to jitter Total length field (IP packets) traffic [See also enabling, traffic shaping.] burst size, defining classifying 2nd 3rd IP Precedence congestion avoidance TCP WRED high-speed transport onset of congestion alerts policing queuing CB-WFQ CQ PQ WFQ rate-limiting repeating segmentation traffic shaping enabling FRTS GTS transaction capabilities application part [See interfaces, TCAP.] transactions MGCP SIP Transfer Allowed (TFA) messages transitive trust transport layer (OSI Reference model) RTP SIP signaling support TCP UDP transport mode (IPsec) trunks 2nd IMT (Inter-Machine Trunk) signaling E&M Type I supervision signaling analog digital tunnel mode (IPsec) tunneling, H.245 TUP (Telephone User Part) 2nd Type I interfaces (E&M signaling) Type II interfaces (E&M signaling) Type III interfaces (E&M signaling) Type IV interfaces (E&M signaling) Type of service fields (IP packets) Type V interfaces (E&M signaling) Index [SYMBOL] [A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [K] [L] [M] [N] [O] [P] [Q] [R] [S] [T] [U] [V] [W] [X] [Z] U reference point UA (user agents) dialog SIP registration process UDP (User Data Protocol) 2nd RUDP UDTs (Unidata Messages) UDTSes (Unidata Service Messages) unicast packets unused ports, disabling UPU (User Part Unavailable) messages user-network messages user-to-network signaling utilities, cRTP Index [SYMBOL] [A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [K] [L] [M] [N] [O] [P] [Q] [R] [S] [T] [U] [V] [W] [X] [Z] VAD (voice activity detection) VCs (virtual circuits) verifying signaling elements, integrity Versatile Interface Processor Distributed CAR (VIP-DCAR) Version field (IP packets) video codecs, H.323 VIP-DCAR (Versatile Interface Processor Distributed CAR) virtual circuits (VCs) Virtual Private Networks (VPNs) 2nd Virtual Private Voice Networks VLR (Visitor Location Register) voice activity detection (VAD) voice mail, POTS voice messaging voice networks, convergence with data networks VoIP-based toll-bypass Vonage, wide-scale deployment VPNs (Virtual Private Networks) 2nd VSAs (vendor-specific attributes) VSC (virtual switch controller) 2nd CDRs packet voice networks XE Index [SYMBOL] [A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [K] [L] [M] [N] [O] [P] [Q] [R] [S] [T] [U] [V] [W] [X] [Z] WANs, edge functions wasted bandwidth, utilizing waveform codecs web sites, Frame Relay Technical Forum web-based collaboration tools weighted random early detection (WRED) weighting techniques IP Precedence policy routing RSVP WFQ (weighted fair queuing) whitelists Wi-Fienabled phones wideband codecs Winchester Blocks WRED (weighted random early detection) Index [SYMBOL] [A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [K] [L] [M] [N] [O] [P] [Q] [R] [S] [T] [U] [V] [W] [X] [Z] XE (Execution Environment), available services Index [SYMBOL] [A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [K] [L] [M] [N] [O] [P] [Q] [R] [S] [T] [U] [V] [W] [X] [Z] zone management, H.323 ... Voice over IP Fundamentals, Second Edition By Jonathan Davidson, James Peters, Manoj Bhatia, Satish Kalidindi, Sudipto Mukherjee Publisher: Cisco Press Pub Date: July 27, 2006 Print ISBN- 10: 1-58705-257-1... ASIST, BPX, Catalyst, CCDA, CCDP, CCIE, CCNA, CCNP, Cisco, the Cisco Certified Internetwork Expert logo, Cisco IOS, the Cisco IOS logo, Cisco Press, Cisco Systems, Cisco Systems Capital, the Cisco Systems logo, Empowering the Internet... Solution Engineering in Integrated Network Systems Engineering He has coauthored Voice over IP Fundamentals and edited Deploying Cisco Voice over IP He has been with Cisco for 10 years in postsales support, marketing, and