Table Of ContentSIP Trunking
Christina Hattingh
Darryl Sladden
ATM Zakaria Swapan
Cisco Press
800 East 96th Street
Indianapolis, IN 46240
ii SIP Trunking
SIP Trunking
Christina Hattingh, Darryl Sladden, and ATM Zakaria Swapan
Copyright © 2010 Cisco Systems, Inc.
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iv SIP Trunking
About the Authors
Christina Hattinghis a member of the technical staff in the Access Routing Technology
Group (ARTG) of Cisco. The ARTG router product portfolio, including the Cisco 2800,
3800, 2900, and 3900 Series integrated services routers and their predecessors, was one
of the first Cisco platforms to converge voice and data starting in the late 1990s by offer-
ing TDM voice interfaces, WAN interfaces, and critical QoS features. Over time sophisti-
cated call control and routing elements were integrated into the router-based platform
making stand-alone VoIP deployments and wide inter-vendor VoIP network interoperabil-
ity possible. In this role, Christina trains Cisco sales staff and customers and consults
widely on voice network deployment and design. She is a long-time speaker of the Cisco
Networkers and CiscoLive conferences. Christina holds a graduate degree in mathemati-
cal statistics and computer science from the University of Pretoria, South Africa.
Darryl Sladdenis a product manager at Cisco and has been with Cisco for more than ten
years. Currently, Darryl is a member of the ARTG at Cisco. The ARTG responsibilities
include the Cisco ISR and ISR G2, AS5000, and the Cisco Unified Border Element
(CUBE). Darryl has been a key contributor to the AS5000 product, CUBE, and several
other VoIP technologies at Cisco for several years. The CUBE and the AS5000 product
lines are widely used by service providers and enterprise customers as border elements
between SIP, H.323, and TDM networks. Darryl has worked with many service provider
and enterprise customers who use CUBE to implement SIP Trunks into both Cisco
Unified Communications Manager (CUCM) and Cisco Unified Communications Manager
Express (CUCME) solutions. Darryl has a degree in mathematics from the University of
Waterloo and holds a patent in the use of voice-based network management, and several
other patents are under consideration.
ATM Zakaria Swapanis a member of the technical staff in the ARTG at Cisco. The
ARTG responsibilities include the Cisco 2800, 3800, 2900, and 3900 Series integrated
services routers and the CUBE. ATM has been a key contributor to SIP, Secure Unified
Communications, Wireless Voice, Network Intelligence, Network Virtualization, RSVP,
and many other developments. ATM has also worked with service providers and enter-
prise customers who use CUBE to implement SIP Trunks into both CUCM and CUCME
solutions. ATM holds an M.S. degree in computer science from Texas A&M University
and a B.S. degree in computer science and engineering from Bangladesh University of
Engineering and Technology (BUET).
v
About the Technical Reviewers
Maulik Shahhas been with Cisco Systems for the past nine years. He has worked with
Unified Communications and Voice over IP (VoIP) systems for the last seven years as part
of the Cisco Technical Assistance Center and Technical Marketing Team. He has helped
design, deploy, and troubleshoot multiple customer VoIP networks. In his current role as
Technical Marketing Engineer, he is focused on Cisco Small Business Solutions including
Cisco SBCS and SIP trunking deployments. He also is a CCIE in Routing and Switching
and Voice.
Vinay Pandeis a technical leader at Cisco, where he is the subject matter expert for SIP
trunking architectures. He works with customers to identify new features and designs
network architectures with a focus on delivering end-to-end solutions. Prior to joining
Cisco, Vinay was a VoIP interop and test lead for Lucent Technologies. He has filed seven
patents in the areas of SIP and NAT transversal for SIP. He has over 12 years of experi-
ence in the field of voice, data, and video network integration.
Dedications
From Christina Hattingh: To Robert Verkroost and my parents for their unfailing encour-
agement and support.
From Darryl Sladden: To Melissa Brown and my mom, sisters, and friends for their
patience and support.
From ATM Zakaria Swapan: To my parents for their great contribution that brings me
here today.
vi SIP Trunking
Acknowledgments
We would like to extend special thanks to Mike Wood, Sibrina Shafique, and Syed
Rahman who were coauthors on some early SIP trunk white papers, the content of which
were adjusted, updated, and reused in this book. These white papers, available on
Cisco.com as of early 2008, represent some of the earliest writing on the start of the
industry transition from TDM to SIP trunking.
We would also like to extend special thanks to the many Cisco employees on whose
expertise, advice, laboratory work, configurations, and examples we drew from for the
technical accuracy of this book. Specifically, to Vinay Pande who is an undisputed expert
in the area of SIP trunking and Francisco Sedano Crippa, one of the many enterprising
Cisco engineers who developed a novel Tcl-based Cisco Unified Border Element (CUBE)
script solution for his customer, which is reused in this book.
Special thanks also go to Tony Banuelos of the Cisco Unified Communication interoper-
ability laboratory, whose unfailing dedication generates countless working configurations
to ease customer network implementations and to the unfailing support and cooperation
of Patty Mertz Medberry who manages the interoperability lab.
Special thanks also go to David Hanes for his expertise on topics involving fax and
modem traffic; to Charles Ganzhorn for video expertise; to Dan Wing and Paul Kyzivat
for their knowledge of SIP and the SIP standards; and to Ed Curry, Charles Demaret, and
Tim Cabeceiras for their expertise on specific SP SIP trunk service offerings.
Thanks also go to various experts who helped with the case studies contained in this
book, including Kees Gerritsen, Zulfi Anees, Kevin Whelan, Mike Haag, and Spencer
Lawes. Thanks also to Kim Haugan Cook for documentation support; to John Heaton for
help in the cost analyses; and to Vivek Bhargava and James Stormes for general expertise
in enterprise SIP trunk design.
Lastly, thanks go to Mike Wood, David Sauerhaft, and Teresa Newell for their leadership
and executive support.
vii
Contents at a Glance
Introduction xix
Part I: From TDM Trunking to SIP Trunking
Chapter 1 Overview of IP Telephony 1
Chapter 2 Trends in IP Telephony 11
Chapter 3 Transitioning to SIP Trunks 31
Chapter 4 Cost Analysis 45
Part II: Planning Your Network for SIP Trunking
Chapter 5 Components of SIP Trunks 57
Chapter 6 SIP Trunking Models 81
Chapter 7 Design and Implementation Considerations 101
Chapter 8 Interworking 141
Chapter 9 Questions to Ask of a Service Provider
Offering and an SBC Vendor 161
Part III: Deploying SIP Trunks
Chapter 10 Deployment Scenarios 191
Chapter 11 Deployment Steps and Best Practices 243
Chapter 12 Case Studies 263
Chapter 13 Future of Unified Communications 297
Index 311
viii SIP Trunking
Contents
Introduction xix
Part I: From TDM Trunking to SIP Trunking
Chapter 1 Overview of IP Telephony 1
History of IP Telephony 1
Basic Components of IP Telephony 2
Microphones and Speakers 2
Digital Signal Processors 3
Comparing VoIP Signaling Protocols 4
Call Control Elements of IP Telephony 5
Other Physical Components of IP Telephony 5
IP Phones 6
IP-PBX 6
Ethernet Switches 6
Non-IP Phone IP Telephony Devices 6
WAN Connectivity Device 6
Voice Gateways 7
Supplementary Services 9
Summary 10
Chapter 2 Trends in IP Telephony 11
Major Trends in IP Communications 12
Enterprise IP Communications Endpoints 13
Desktop Handset Trends 15
Enterprise Softphone IP Phone Trends 16
Enterprise WiFi IP Phone Trends 17
Cellular Phone Trends Within Enterprises and
Their Effects on SIP Trunking 18
Endpoint Trends in Enterprises and Their Effects on SIP Trunk 19
Feature Trends in SIP Trunking Within the Enterprise 20
Feature Trends in SIP Trunking Between Enterprises 22
Feature Trends in SIP Trunk for PSTN Access 24
Feature Trends in Advanced SIP Trunking Features from
Service Providers 26
Feature Trends for Call Centers Services from SIP
Trunk Providers 28
Summary 30
ix
Chapter 3 Transitioning to SIP Trunks 31
Phase I: Assess the Current State of Trunking 33
Phase II: Determining the Priority of the Project 34
Phase III: Gather Information from the Local SPs 35
Phase IV: Conducting a Pilot Implementation of SIP Trunks for
PSTN Access 35
Phase V: Transitioning a Live Department to SIP Trunks 37
Phase VI: Transition to SIP Trunking for Call Center Locations 38
Phase VII: Transition to SIP Trunking at Headquarters Locations 39
Phase VIII: Transition to SIP Trunking of Branch Locations 40
Phase IX: Transition Any Remaining Trunk to SIP Trunking 41
Phase X: Post Project Assessment 41
Summary 43
Chapter 4 Cost Analysis 45
Capital Costs 46
Cost of Installation 47
Cost of Equipment 47
Border Element Chassis Cost 48
Port Cost 48
Digital Signal Processor (DSP) Cost 48
Software License Cost 49
Monthly Recurring Costs 49
Port/Line Charge 49
Bandwidth Charge 50
Service Level Agreement Charge 50
Cost of Usage 51
Pay as You Use 51
Bundled Offer 51
Burstable Shared Trunks 52
Cost of Spike Calls 53
Cost of Security 53
Cost of Expertise/Knowledge 54
Other Areas of Costs and Savings 54
Summary 55
Further Reading 55
