Compliments ofFloyd Earl Smith

7th Ribbon
Special EditionSession Border
Controllers
7th Ribbon Special Edition

By Floyd Earl Smith

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

Session Border Controllers For Dummies®, 7th Ribbon Special Edition
Published byJohn Wiley & Sons, Inc.
111 River Street
Hoboken, NJ 07030-5774

www.wiley.com

Copyright © 2024 by John Wiley & Sons, Inc.
No part of this publication may be reproduced, stored in a retrieval system or transmitted in any
form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise,
except as permitted under Sections 107 or 108 of the 1976 United States Copyright Act, without
the prior written permission of the Publisher. Requests to the Publisher for permission should be
addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ
07030, (201) 748-6011, fax (201) 748-6008, or online at http://www.wiley.com/go/permissions.
Trademarks: Wiley, the Wiley logo, For Dummies, the Dummies Man logo, A Reference for theRest of Us!, The Dummies Way, Dummies.com, Making Everything Easier, and related trade dress
are trademarks or registered trademarks of John Wiley & Sons, Inc. and/or its affiliates in the
United States and other countries, and may not be used without written permission. Ribbon
Communications and the Ribbon Communications logo are registered trademarks of Ribbon
Communications. All other trademarks are the property of their respective owners. John Wiley &Sons, Inc., is not associated with any product or vendor mentioned in this book.
LIMIT OF LIABILITY/DISCLAIMER OF WARRANTY: WHILE THE PUBLISHER AND AUTHORS HAVEUSED THEIR BEST EFFORTS IN PREPARING THIS WORK, THEY MAKE NO REPRESENTATIONS
OR WARRANTIES WITH RESPECT TO THE ACCURACY OR COMPLETENESS OF THE CONTENTS OF
THIS WORK AND SPECIFICALLY DISCLAIM ALL WARRANTIES, INCLUDING WITHOUT LIMITATIONANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
NO WARRANTY MAY BE CREATED OR EXTENDED BY SALES REPRESENTATIVES, WRITTEN SALES
MATERIALS OR PROMOTIONAL STATEMENTS FOR THIS WORK. THE FACT THAT AN ORGANIZATION,WEBSITE, OR PRODUCT IS REFERRED TO IN THIS WORK AS A CITATION AND/OR POTENTIAL SOURCE
OF FURTHER INFORMATION DOES NOT MEAN THAT THE PUBLISHER AND AUTHORS ENDORSE
THE INFORMATION OR SERVICES THE ORGANIZATION, WEBSITE, OR PRODUCT MAY PROVIDEOR RECOMMENDATIONS IT MAY MAKE. THIS WORK IS SOLD WITH THE UNDERSTANDING THAT
THE PUBLISHER IS NOT ENGAGED IN RENDERING PROFESSIONAL SERVICES. THE ADVICE AND
STRATEGIES CONTAINED HEREIN MAY NOT BE SUITABLE FOR YOUR SITUATION. YOU SHOULD
CONSULT WITH A SPECIALIST WHERE APPROPRIATE. FURTHER, READERS SHOULD BE AWARE
THAT WEBSITES LISTED IN THIS WORK MAY HAVE CHANGED OR DISAPPEARED BETWEEN WHEN
THIS WORK WAS WRITTEN AND WHEN IT IS READ. NEITHER THE PUBLISHER NOR AUTHORSSHALL BE LIABLE FOR ANY LOSS OF PROFIT OR ANY OTHER COMMERCIAL DAMAGES, INCLUDINGBUT NOT LIMITED TO SPECIAL, INCIDENTAL, CONSEQUENTIAL, OR OTHER DAMAGES.

For general information on our other products and services, or how to create a custom For
Dummies book for your business or organization, please contact our Business Development
Department in the U.S. at 877-409-4177, contact info@dummies.biz, or visit www.wiley.com/go/custompub. For information about licensing the For Dummies brand for products or services,
contact BrandedRights&Licenses@Wiley.com.
ISBN: 978-1-394-19693-7 (pbk); ISBN: 978-1-394-19694-4 (ebk). Some blank pages in theprint version may not be included in the ePDF version.

Publisher’s Acknowledgments
We’re proud of this book and of the people who worked on it. Some of thepeople who helped bring this book to market include the following:
Project Manager and Editor:
Carrie Burchfield-Leighton

Client Account Manager:
Jeremith Coward

Acquisitions Editor: Traci Martin

Key Ribbon Contributors:
Daniel Teichman, Greg Zweig

Sr. Managing Editor: Rev Mengle

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

Table of Contents
INTRODUCTION................................................................................................ 1
About This Book.................................................................................... 1
Icons Used in This Book........................................................................ 2
Beyond the Book................................................................................... 2
CHAPTER 1:

Protecting Real-Time Communications
with SBCs............................................................................................. 3
Looking at the SBC’s Role..................................................................... 3
Understanding the Need for SBCs...................................................... 6

CHAPTER 2:

Identifying the Key Requirements of an SBC....... 11
Normalizing SIP................................................................................... 11
Transcoding Calls................................................................................ 12
HD voice.......................................................................................... 13
Bandwidth restrictions.................................................................. 14
Dealing with NAT Traversal................................................................ 14
Fax and Tone Detection...................................................................... 15
Performance, Scalability, Resiliency.................................................. 15

CHAPTER 3:

Virtualization and Cloud-Native SBC.......................... 17
Defining a Virtual SBC......................................................................... 17
Discovering a Cloud-Native SBC........................................................ 19

CHAPTER 4:

Deploying SBCs for Different Use Cases................... 23
Unified Communications.................................................................... 23
Enterprise Connectivity...................................................................... 24
Mobile................................................................................................... 25
IP Multimedia Subsystem (IMS) Networks....................................... 26
WebRTC................................................................................................ 27
Contact Center..................................................................................... 28

CHAPTER 5:

Exploring the Contact Center........................................... 29
Identifying Contact Center Needs..................................................... 29
Using an SBC to Improve Efficiency.................................................. 30

Table of Contentsiii

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

CHAPTER 6:

Determining the Value and ROI of an SBC............. 33
Reducing Costs with Intelligent Policies........................................... 33
Increasing Efficiency............................................................................ 34
Minimizing Costly Downtime............................................................. 36
Consolidating Multiple Functions...................................................... 36
Getting Real about Cost Savings........................................................ 37

CHAPTER 7:

Ten Reasons to Choose a Ribbon SBC........................ 39
Robust Security.................................................................................... 39
Peak Performance............................................................................... 40
High-Scale Transcoding...................................................................... 40
Advanced Media Support................................................................... 40
Interoperability.................................................................................... 41
Multiple Certifications......................................................................... 41
Seamless Scalability............................................................................ 42
Virtual and Cloud Native..................................................................... 42
Centralized Policy and Routing Control............................................ 43
Proven Track Record........................................................................... 43iv

Session Border Controllers For Dummies, 7th Ribbon Special Edition

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

Introduction

In the early days of online communications, many people usedphone lines to connect to online services, the Internet, and theweb. Today, ironically, a great deal of telephone service is provided over Internet Protocol (IP) networks. And even plain old
telephone service (POTS) that uses traditional phone lines may be
managed remotely via the Internet.

IP-enabled communications are far more flexible and ­capable —and operate at lower cost — than the landlines of yesterday.
Today’s real-time communications no longer just consist of voice
calls. They also include team collaboration, video conferencing,
instant messaging, presence, and desktop sharing.
Making these applications work together seamlessly requires asignaling protocol, known as Session Initiation Protocol (SIP),
which is used to establish communication sessions between
parties. As powerful as SIP is, it isn’t without challenges. These
include differences in implementation between vendors and security concerns involved when transporting communications traffic
across the Internet.
A session border controller (SBC) is designed to control real-timecommunications traversing an enterprise or service provider’sIP network. Initially developed as a stand-alone device, SBCs are
now also available as software running on commodity servers.
SBCs handle all the signaling and media functions, such as interworking and transcoding, required to make SIP-based communications work seamlessly.

About This Book
Session Border Controllers For Dummies, 7th Ribbon Special Edition,is your introduction to the wonderful world of SBCs. This bookconsists of seven short chapters that explore» What SBCs are and why they’re needed (Chapter 1)» What else an SBC does in a communications network(Chapter 2)

Introduction

1

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

» How a virtual or cloud-native SBC can benefit enterprises
and service providers (Chapter 3)» SBC use cases and real-world deployment scenarios(Chapter 4)» How a contact center is dependent on an SBC (Chapter 5)» How to determine the value and ROI of an SBC (Chapter 6)» Why your organization needs a Ribbon SBC (Chapter 7)

Icons Used in This Book
Throughout this book, I occasionally use special icons to callattention to important information. Here’s what to expect:
This icon points out information that you should commit to yournon-volatile memory, including important dates.

The Tip icon points out information that aids in your understanding of a topic or that may save you time, money, or a headache.

This information tells you to steer clear of things that may costyou big bucks, are time sinks, or are just poor practice in using
an SBC.

Beyond the Book
This book gives you a better understanding of SBCs, but if you’releft wanting more, visit the Ribbon website at www.rbbn.com.
There you can learn more about how Ribbon’s expertise helps
customers deploy, manage, and optimize their SBCs.

2

Session Border Controllers For Dummies, 7th Ribbon Special Edition

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

IN THIS CHAPTER»» Understanding the role of the SBC in
real-time communications»» Recognizing why enterprises and service
providers need SBCs

Chapter

1

Protecting Real-Time
Communications
with SBCs

R

eal-time communications in modern businesses include
phone calls, video conferencing, chat, text messaging,desktop sharing, and team collaboration. In this chapter,
you learn how a session border controller (SBC) enables andsecures enterprise and service provider real-time communication
infrastructure and services.

Looking at the SBC’s RoleAn SBC secures and controls real-time communications by admitting end devices to the session (or not admitting them, as needed),
and then directing communications between the end devices andany intermediate devices on the network. Common examples area Voice over IP (VoIP) call between two phones or a video conference that connects multiple devices.

CHAPTER 1 Protecting Real-Time Communications with SBCs

3

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

SBCs are deployed at the network perimeter (that is, at the
network’s border) so that they can control and secure real-timecommunications for both enterprises and service providers. An
SBC performs the following functions:» Securing the real-time communications network: An SBC

protects and secures real-time communications from various
threats such as spoofing, distributed denial-of-service (DDoS)
attacks, and toll fraud. The SBC secures real-time communications by• Acting as a back-to-back user agent (B2BUA), which allows
the SBC to hide the topology of the internal Internet
Protocol (IP) network, making it difficult or impossible forbad actors to gain access to potentially vulnerable partsof the network• Encrypting both signaling and media to maintain privacy
and prevent communications from being illegallyintercepted or tampered with• Detecting and preventing DDoS attacks so that they don’t
impair network and service performance• Enabling call admission control and dynamic blocking ofrogue endpoints to avoid telephony denial-of-service(TDoS) threats and toll fraud

Session Initiation Protocol (SIP) is a signaling protocol used
for initiating, maintaining, modifying, and terminating
real-time communication sessions between IP devices.
Real-time Transport Protocol (RTP) is a network standard
designed for transmitting real-time voice or video across
IP networks.

» Enabling SIP trunking: An SBC provides a demarcation or

termination point of the SIP and RTP connection (often
referred to as a SIP trunk) into a communications network.
An SBC provides the security, interoperability, and some of
the intelligence (for example, where to route SIP calls)
needed to safely connect SIP trunks with your network. The
SIP service provider also needs an SBC on its side of the SIP
trunk to protect its network. You can think of an SBC as
providing a SIP firewall that includes a host of value-added
services such as intelligent routing controls, signaling andmedia interworking, resiliency, and the ability to ensure ahigh quality of service between different network devices.

4

Session Border Controllers For Dummies, 7th Ribbon Special Edition

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

Savings from SIP trunking, trunking consolidation, and themove to VoIP and unified communications (UC) can reduce
traditional enterprise telecom bills by up to 75 percent, withhigher quality of service. Additionally, the SBC can provide
secured access to SIP trunking services, so an enterprise canmaintain security while saving money.

» Interconnecting and interworking networks andprotocols: An SBC provides a smooth experience in terms ofinterconnecting and interworking between different
networks and the protocols running over them. Specifically,
the SBC performs tasks such as• Dealing with SIP variants: When SIP was developed andstandardized, a lot of flexibility still existed in how specificparameters could be used and populated. This meansthat SIP has a lot of variants based on different vendor
implementations. An SBC can translate these variants
between devices (a process known as SIP normalization,
covered in more detail in Chapter 2) so that calls go
through with all their features intact.

• Translating protocols: Different UC solutions may utilize
different audio codecs and other protocols that aren’t
completely supported on both sides of the session. The
SBC knows all these protocols and can translate ortranscode between them on the fly.

» Acting as session traffic cop: The SBC is the gatekeeper

to SIP-based services in an enterprise or service provider
network. In this role, SBCs perform session admission
control, which is the process of determining who has accessto the network. This makes the SBC the traffic cop of a SIP
network, keeping your SIP highways safe and orderly andcreating and accessing three lists: allow lists, block lists, andgrey lists (discussed in the later section, “Understanding the
Need for SBCs” in this chapter).

» Intelligent routing and policy controls: In larger deploy-ments, where multiple SBCs are installed at multiple network
connectivity points, the task of individually configuring
routing and policies on all SBCs can be tedious and expensive. An alternative to localized policy control is further
centralization using a primary policy server to dynamically
propagate a single set of routing and policy rules to each SBC
on the network.

CHAPTER 1 Protecting Real-Time Communications with SBCs

5

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

Alternatives to SBCs include virtual private network (VPN) tunnels and firewalls, but each of these alternatives has somedisadvantages:» VPN tunnels: A VPN can cause trouble when there’s a needto look inside the packets encapsulated in the VPN to routecalls and provide services. To enable this, VoIP packets must
be decrypted and acted on — removing the end-to-end
encryption element that keeps a VPN secure.

» Firewalls: A firewall can be configured to allow VoIP traffic topass through the network to client devices within the
network. The problem is that VoIP (and UC) sessions are
exceedingly dynamic. Sessions are set up and torn down
frequently and in large numbers. Additional services areoften added during the middle of a call (for example, whensomeone begins to instant message another user during a
conference call, or when someone shares a picture or video
during a voice call). Typically, a firewall just isn’t capable ofhandling this kind of dynamic service provisioning.

Understanding the Need for SBCs
SBCs were initially deployed within service provider networks.
SBCs ensure that

» Real-time communication traffic is properly routed between
network providers.

» Differing protocols are understood so that the call can bedelivered across different networks.

» Calls are secure.

As time-division multiplexing (TDM) PBXs and contact centers
have been replaced by IP-based platforms — and, more recently,
by cloud-based services — VoIP adoption has become more common in the enterprise, and SBCs have been increasingly deployedat the border between an enterprise’s network and the carrier’s
network. The first driver of SBC implementation within real-timecommunication networks is security.

6

Session Border Controllers For Dummies, 7th Ribbon Special Edition

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

VoIP (as well as other session-oriented applications) is an application that, by its very nature, is exposed to devices and networks
that are beyond the control of an enterprise or a network provider. VoIP isn’t like traditional telephony in which a very highly
circumscribed set of devices, protocols, and private networks
was involved in the process of placing and carrying calls. In theold days when you placed a phone call, the call was placed on an
approved device and carried across the phone company’s private
network.
Like other IP applications, VoIP can be carried over one or more
public networks. Calls can be initiated or completed on devices,such as personal computers (PCs) or smartphones, using VoIP
applications that aren’t under the control and regulation of anenterprise or the phone company. While this enables new features, greater flexibility, and lower costs, it also makes the VoIP
world considerably more vulnerable, broadening the attack surface to the same kinds of security threats as any other Internet
service.
Many hackers consider telephony of all kinds fair game for disruption. Steve Jobs and Steve Wozniak, for instance, were involved
in “phone phreaking” before they founded Apple in 1976. Service
providers are likely to face talented and determined hackers, sorobust effort and constant vigilance are a requirement.
Some common VoIP attacks include» Service theft and fraud: Attackers accessing a VoIP system
to fraudulently make calls and use network resources
without paying for them

» Spoofing: Deliberately modifying or disguising an identity(for example, caller ID) on the network» DDoS/TDoS attacks: Flooding a network server or SBC withrequests to overwhelm its available resources — a common
way to attack and disrupt contact centers» Registration storms: Like a DDoS attack, in which many

simulated devices (typically hundreds of thousands tomillions) simultaneously attempt to register with a SIP server
in a UC network to overwhelm its available resources

CHAPTER 1 Protecting Real-Time Communications with SBCs

7

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

An SBC employs various techniques to protect enterprises andservice providers from cyberattacks against their real-time communication networks, including the following:» Support for media and signaling encryption: Encryption

prevents unauthorized parties from eavesdropping on
real-time communications or tampering with a call. Encryption
also provides an authentication mechanism to verify that aclient is who they say they are. The signaling component of
real-time communications is typically secured by Transport
Layer Security (TLS) or IP Security (IPsec), while the media layer
is secured by Secure Real-time Transport Protocol (SRTP).

» Dynamic pinholing: A pinhole is a port opened in a firewall

to allow an application to access the IP network. Leaving aport open for an extended period can potentially enable asecurity breach. SBCs programmatically create pinholes
and leave them open for only the short period that a sessionis active to minimize security exposure. At the end of asession — for example, a voice call — the SBC will close thepinhole. SBCs can then reopen ports as needed to allow
trusted applications to send and receive data.

» Topology hiding with B2BUA: A B2BUA controls SIP calls bya logical or virtual proxy configured for the call. This agent
sets up the pathways across the network for both signaling
and media. B2BUA causes all signal and media traffic to run
through the SBC and hides the topology, or architecture, ofthe network so clients aren’t shown private IP addresses ofservers and devices in the network. The result is a network
that’s easily accessible to clients for making and receiving
calls but whose “innards” are effectively invisible, whichmakes them less vulnerable to attack.

» List monitoring: The SBC’s policy management function

monitors incoming requests and calls, using rules to identify
devices, referred to as endpoints, which are and aren’t
abusing network resources, and maintains certain lists
including• Allow lists: Devices that always have access to the
network• Block lists: Devices that never have access to the network• Grey lists: Devices that sometimes have access to the
network

8

Session Border Controllers For Dummies, 7th Ribbon Special Edition

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

IPv6 HAS ARRIVED
The IP variant (IPv4) that powered the Internet for many years started
to have an issue. IPv4 used a 32-bit address space, which meant that
it was limited to only about 4.3 billion addresses — and it ran out ofavailable addresses in 2015.
IPv6, introduced in 2012, increased the address space to 128 bits,
which meant that there were 340,282,366,920,938,
463,374,607,431,768,211,456 possible addresses (that’s 340 undecillion, 282 decillion, 366 nonillion, 920 octillion, 938 septillion, 463 sextillion, 463 quintillion, 374 quadrillion, 607 trillion, 431 billion,
768 million, 211 thousand and 456 — seriously).
The move to IPv6 caused other issues. For example, not all networks
were configured to support IPv6. When two clients wanted to communicate, and one was on an IPv4 network and the other on IPv6, something needed to be placed in the middle to help them communicate.
An SBC serves this purpose. It resolves these issues in two ways:• An SBC can be dual stacked, meaning it contains the network stacksoftware (the basic network protocol software suite) for both IPv4
and IPv6. The SBC can communicate using both versions of IP; forinstance, it can connect to an IPv6-only smartphone using IPv6
while connecting to an IPv4 server using IPv4.

• The SBC can act as an interworking agent between an IPv4 net-

work and an IPv6 network. In this case, the SBC can translate all
traffic flowing between an IPv4 and an IPv6 network on the fly, as
it crosses the network border.

CHAPTER 1 Protecting Real-Time Communications with SBCs

9

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

IN THIS CHAPTER»» Understanding SIP and call transcoding»» Translating NAT traversal»» Learning the facts about fax and tone
detection»» Supporting video»» Ensuring performance, scalability, andresiliency in an SBC

Chapter2

Identifying the Key
Requirements of an SBC

Asession border controller (SBC) does much more thanjust provide security. In fact, many in the telecommuni­
cations industry say that it’s the security that getscustomers interested, but it’s the other functionality in an SBC
that makes the sale. This other functionality is all about SBCs
making Voice over Internet Protocol (VoIP) calls and real-timecommunications (RTC) work in situations where they otherwise
might not work. And, beyond that, SBCs simply make VoIP and
RTC services work better.
In this chapter, you find out about all the other essential functionsof an SBC.

Normalizing SIP
Session Initiation Protocol (SIP) is the primary protocol that
establishes the connection between two endpoints and termi­
nates the connection when the call is finished. At the most basic
level, SIP is the VoIP equivalent of the dialing tones that directed

CHAPTER 2 Identifying the Key Requirements of an SBC

11

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

old-fashioned analog calls to the right switches and across phone
networks. SIP is the common language that telecom providers andequipment makers use to communicate with each other.
SIP is a communications standard drafted by the Internet­Engineering Task Force (IETF) in the late 1990s. The standard,
however, is more of a series of recommendations and sugges­
tions on how SIP should be implemented than a conclusive
specification. The actual SIP implementations are left up to indi­vidual engineers and vendors, resulting in SIP variations that are­technically in compliance with the published SIP standards but
not necessarily interoperable with one another.
Enough variations exist in SIP that sometimes two systems con­necting to each other using SIP find that they aren’t speaking
the same language — the basics are all there but with differing
syntax and dialects in what otherwise appears to be a common
language (kind of like American English versus British English).
There’s just enough difference to cause confusion. When two peo­
ple are talking, such confusion can be overcome by context or by asimple “huh?” But when two devices are talking, that simply isn’t
going to happen.
An SBC must be able to speak all the different dialects of SIP and
do on-the-fly translations in both directions. So, if a call is cross­ing a border between a system using Dialect X and another systemusing Dialect Y, the SBC must find the parts of Dialect X and Y that
don’t quite match up and convert them back and forth as the callmoves across the SBC. It’s not rocket science in concept, but it’s
hard to do, especially within milliseconds; the best SBCs make thewhole process transparent and seamless.

Transcoding Calls
Another of the SBC’s jobs is to transcode, or change, codecs as
media sessions pass through the SBC. The SBC knows which
codecs are supported on each side of the network border and isrequired to decode and then re-encode the voice or video signal as
it crosses the network border by using a combination of special­ized software or special-purpose digital signal processors (DSPs).

12

Session Border Controllers For Dummies, 7th Ribbon Special Edition

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

Many codecs — the encode/decode algorithms that compress
voice and other signals, such as video streaming across the net­
work in a videoconferencing environment — are in use in various
VoIP and unified communications (UC) systems. Low-bandwidthand high-bandwidth video and voice codecs are designed to workon various devices, such as» Computers and tablets» Dedicated VoIP phones» Mobile smartphones
In a VoIP call (or any real-time, session-based communication,
for that matter), there are often differing capabilities to support
codecs. So if an enterprise’s private branch exchange (PBX) or
contact center supports one specific codec and an incoming call isusing a different codec, the SBC will understand both codecs andtranscode between the two codec types in real time and in both
directions as the call passes through it. However, some codecs
may not be implemented on a device, for a few reasons:» The developers haven’t gotten around to it yet.
» The software licensing fee is too high.
» The device has a relatively “slow” CPU and can’t handle thecodec computationally.

Transcoding in SBCs frequently comes into play in two specificinstances; both are covered in this section.

HD voice
The sound quality of voice calls in general took a step backward
over the years as convenience (mobile phones) and econom­
ics (VoIP) drove the replacement of traditional landline phones
with a range of new devices. However, high-definition (HD) voice
reversed that trend. HD voice can reproduce a greater range of
frequencies at higher clarity by using wideband codecs rather
than traditional narrowband codecs (so called because they cut off
both the top and bottom frequencies found in a person’s voice).
You may have heard the effects of this firsthand because many
popular cloud-based collaboration tools such as Teams, Zoom,
Webex, and so on use wideband codecs.

CHAPTER 2 Identifying the Key Requirements of an SBC

13These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

There’s a gotcha to HD voice: There’s no single codec used byevery HD voice-capable system. However, having an appropriate
SBC — one with robust transcoding capabilities — in the middleof the call solves the problem. The SBC can transcode and keep
the call HD all the way, but a lot of software and/or hardware aredoing some heavy lifting behind the scenes.

Bandwidth restrictions
Sometimes a call is made to someone who’s connected to an older
mobile network with poor infrastructure. Other times, a call ismade to a person in a home office or a hotel with a limited Wi-Fi
connection. To address these bandwidth restrictions, codecs that
trade fidelity and audio/video quality for greater compression areavailable, and they use less bandwidth.
Users may not want to default to these low-fidelity codecs all thetime, but sometimes they’re necessary over at least part of thecall’s path. An SBC sitting between network segments can recog­
nize this situation and transcode to and from lower-bandwidth
codecs when required. This situation is much better than rely­
ing on the VoIP clients themselves to do this kind of calculation
upfront, especially because not all clients support all codecs.

Dealing with NAT Traversal
Network Address Translation (NAT) converts a public IP address
to a private, non-routable IP address. NAT is used because there
aren’t enough public IP addresses available in the world to assign
every device its own unique IP address.
Internet Protocol version 6 (IPv6) is the newer IP address schemathat will eventually replace traditional IPv4 addresses. IPv6
increases the number of available IP addresses and reduces theneed for NAT. The gradual adoption of IPv6 is another reason touse an SBC, because the SBC has intelligence that enables IPv4
and IPv6 network segments to talk to each other. See Chapter 1 tofind out more about IPv6.
The challenge with NAT is that creating an end-to-end session
is difficult because the IP address of a device using NAT isn’t apublic, routable IP address. This creates issues with end-to-end

14

Session Border Controllers For Dummies, 7th Ribbon Special Edition

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

sessions, like VoIP, and requires some translation to happen
between public and private addresses — translation beyond whata network router can do.
Many SBCs explicitly support what’s known as NAT traversal,
providing the ability to work with VoIP session packets and giving
them the instructions they need to get through the NAT routerand to the actual device that’s at the other end of the session. NAT
traversal requires a significant amount of processing power in the
SBC because of the large number of devices participating in VoIP
and other sessions that may be located behind a NAT gateway.

Fax and Tone Detection
Legacy technologies sometimes linger on well past their “sellby” date — and the network needs to support them. A ­prominent
example is facsimile (fax) technology. There are still people out
there (in areas such as medicine, law, and real estate) using fax
machines every single day of the week. VoIP systems would, if
they could form opinions, probably be opposed to this, but thereality remains.
An SBC, however, can come to the rescue here by incorporating
tone detection (the ability to recognize and act on standard analog
telephone touch tones) to recognize and then properly route thatawful screech that precedes a fax.

Performance, Scalability, Resiliency
SBCs need to be powerful and robust, with the capacity andredundancy not only to handle the average number of calls com­
ing through the system simultaneously but also to scale up andhandle peak loads. This is especially critical for contact centers,
where every call can equate to a sale or improve customer satis­
faction. When evaluating an SBC’s performance, scalability, andresiliency, consider the following factors:» CPU utilization: The SBC does a lot of computationallycomplex work, such as SIP translation, intelligent routing,

CHAPTER 2 Identifying the Key Requirements of an SBC

15

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

centralized call recording (SIPRec), and other functions in realtime. CPU utilization during both normal and peak periods
should allow for sufficient overhead.

» Concurrent calls (or sessions) supported: How many

concurrent calls is the SBC rated for, and how does thismatch your network’s usage patterns? If your usage grows
and begins to exceed the capacity of your SBC, what are yourupgrade options?

» Redundancy: Put a different way, this means “avoiding

single points of failure.” SBCs perform a mission-critical rolefor enterprises and service providers, so you need to knowwhat your redundancy options are and which of those
options will work best for your needs.

» Registration rate: How many clients can the SBC register ina fixed period? When a lot of users are connecting at once,
make sure that the SBC can handle it.

» QoS policies: The QoS policy of a network and prioritizationof data flows are implemented by the SBC. QoS policies
perform such functions as traffic policing, resource allocation, rate limiting, and call admission control (CAC).

16

Session Border Controllers For Dummies, 7th Ribbon Special Edition

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

IN THIS CHAPTER»» Defining the virtual SBC»» Recognizing the key functions andbenefits of a cloud-native SBC

Chapter3

Virtualization and
Cloud-Native SBCI

n this chapter, you learn how virtualization and cloud-native
design work and how your organization can benefit from a virtual or cloud-native session border controller (SBC).

Defining a Virtual SBC
Virtualization abstracts software (such as an operating system
and installed applications) from the underlying physical hardware on which the software is running. Server virtualization isperhaps the most well-known and widely implemented virtualization technology. But wait, there’s more! Other common typesof virtualization include» Application virtualization» Desktop virtualization» Storage virtualization» Network virtualization

CHAPTER 3 Virtualization and Cloud-Native SBC

17

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

Communications systems use virtualization in the design,
deployment, and management of network services by separating
network functions from hardware devices. This process removes
the need for you to purchase dedicated hardware such as routers,
firewalls, and SBCs, among others.
A virtual SBC is an SBC implemented entirely in software that canbe deployed on commercial, off-the-shelf servers. In many cases,
the core of the SBC software is the same code that executes in a
hardware-based SBC. However, because the virtual SBC is implemented in software, it can be easily deployed on virtual machines
in an on-premises data center, or in a private or public cloud.
Some of the benefits of virtualization include» Efficient resource utilization: Before virtualization, many

data centers used about 10 percent of their total capacity,
meaning that nearly 90 percent of their capacity went
unused. Virtualization enables organizations to run multiple
virtual workloads on a single physical host server, maximizing the utilization of resources such as compute, memory,and storage.

» Reduced operating expenses: The cost of rack space,

power, cooling, and network connectivity in a data center isincrementally higher for each physical server or appliancethat’s deployed. Virtualization enables SBCs and/or otherapplications or network functions to be deployed on a single
physical server, thereby reducing costs to the organization.

» Low total cost of ownership (TCO): Virtual SBCs provide amuch lower TCO than hardware-based SBCs because they
run on less expensive, off-the-shelf server hardware. Virtual
SBCs also support a pay-as-you-grow model, meaning thatbusinesses don’t have to pay for system capacity that
isn’t yet needed.

» Faster time to market: Virtual SBCs allow service providers

to deploy new network services very quickly to supportchanging requirements and seize market opportunities as
they arise. This flexibility also reduces risks associated withrolling out new services because service providers can easily
try out and modify new service offerings to meet the needsof their customers.

18

Session Border Controllers For Dummies, 7th Ribbon Special Edition

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

» Greater agility: Service providers must be able to quickly

scale their services up or down to meet changing market
demands. They also need to innovate quickly and get thoseinnovations to market as quickly and easily as possible.
Virtual SBCs allow for services to be delivered to customers
on private or public clouds to achieve greater agility.

Discovering a Cloud-Native SBC
Virtualization is a key enabling technology for software-only
SBCs, but to truly leverage the cloud means going beyond virtualization to adopt cloud-native design and operational principles.
A cloud-native SBC» Takes advantage of microservices design, containers, andautomated life cycle management» Leverages automation, enabling rapid provisioning» Is characterized by its elasticity — its ability to auto-scale on
demand» Has efficient and reliable resource allocation» Delivers performance at scale» Has integration based on open APIs and participates in an
open telemetry observability framework» Can be incorporated into flexible, subscription-based
licensing models

When choosing a cloud-native SBC, look for the following important capabilities and features:» Run-time-ready instantiation: Deploying real-timecommunications in the cloud requires the ability to instantiate an SBC application as rapidly as the real-time service
itself. To achieve this level of responsiveness, the SBC needs
to be designed using microservices, each of which isinstantiated as a separate workload — that is, as a set ofcomputing resources that are required to run the microservice. These workloads are packaged using containers andmanaged using automated life cycle management software
such as Kubernetes.

CHAPTER 3 Virtualization and Cloud-Native SBC

19

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

The result of being run-time ready is service velocity with
operational efficiency, because it’s possible to instantiate arunning, configured SBC that’s immediately capable of callprocessing without the need for operator intervention.

» Elasticity (auto-scaling): The advantage of a cloud-nativeenvironment is the ease, speed, and ultimately costeffectiveness with which an SBC can be auto-scaled. With
automated life cycle management, provided by Kubernetes,
SBC workload scaling can match traffic d­ emand in real time.
This rapid scale-up/scale-down functionality is the very
essence of elasticity.
Achieving elasticity also means that instantiation is optimized
for both horizontal scaling (adding more workloads) andvertical scaling (adding more capacity or performancewithin a workload).

» Optimal load balancing: Load balancing is the mechanismthat optimizes resource utilization, ensuring that traffic isevenly balanced across multiple service instances, in alignment with the dynamic traffic load. With load balancing,variances in traffic are optimized across aggregate capacity;
as a result, solution resiliency is increased by avoiding server
overload situations that could potentially cause processing
failures. Furthermore, traffic will be rebalanced automaticallyin the event of a workload failure.
For the SBC application, load balancing must have knowledge of session persistence and the performance status ofeach workload.

» Resiliency and high availability: Certain attributes of an

SBC are considered table stakes for deployment. Resiliency
and high availability (HA) fit this designation. One goal of acloud-native design based on microservices is to be able toexceed the fault tolerance that was found in more traditional
hardware deployments but to do so without the overheadof multiple hardware platforms. In a cloud-native design, it’s
possible to support many different redundancy options. For
example, this would include active–active configurations, N:1(this is “N” active nodes backed up by “1” standby node), and
N:M (this is “N” active nodes backed up by “M” standby
nodes) configurations. A high-availability implementation
can maintain session and media continuity in the event of
the failure of any workload.

20

Session Border Controllers For Dummies, 7th Ribbon Special Edition

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

» Performance at scale: Performance at scale gets to the very

heart of how an ideal SBC is designed and why moving SBCs
to a cloud-native deployment model, rather than using
traditional, proprietary hardware devices, is imperative.
The cloud-native deployment model, based on microservices
and containers, makes it possible to enable (turn on) featurecapabilities such as encryption, interworking for IPv4 to IPv6
or for Real-time Transport Protocol (RTP) to Secure Real-time
Transport Protocol (SRTP), and SIP header manipulation, while
also ensuring that they have no impact on overall session
performance. For example, call control functions scale basedon the rate of calls per second, which is a very different
measure than how a transcoding service needs to scale, basedon packets per second. Scaling performance for specificmicroservices also means that a cloud-native SBC is capable ofhandling sustained denial-of-service (DoS) attacks or registration floods without negative impact on call performance orcall quality.

» Open APIs and integration with an observability frame-

work: Network functions such as an SBC don’t work in a
vacuum; they’re part of an overall network infrastructure tosecure and ensure the delivery of real-time communications. As
such, they need to fit into the management infrastructure thatan enterprise or service provider has in place. For a cloud-native
SBC, this means support for open APIs and integration with anopen telemetry-based observability framework.
Integration for monitoring metrics and logs, and interfacingwith open source/third-party tools such as Prometheus andEFK (Elasticsearch, Fluentd, and Kibana), reduces the friction
for seamlessly fitting into a framework that is common
across multiple cloud-native applications or workloads. For
example, while resource utilization statistics are commonlyused for life cycle management and load balancing, visibility
to them can also be used for capacity planning across all
resources in a cloud deployment.

» Subscription-based, network-wide licensing: A subscriptionbased licensing model is appropriate for virtual and cloudnative deployments. Instead of traditional licensing that was
typically coupled with a system’s capacity, a subs­cription-based
licensing model aligns with the dynamic usage of resources.
By extension, licenses need to be available on a network-widebasis because virtual or cloud-native deployments remove theconstruct of a license tied to a physical device or location.

CHAPTER 3 Virtualization and Cloud-Native SBC

21

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

IN THIS CHAPTER»» Supporting unified communications»» Connecting the enterprise»» Securing mobile communications»» Enabling WebRTC»» Improving the contact center experience

Chapter

4

Deploying SBCs forDifferent Use Cases

S

ession border controllers (SBCs) play a role in many different types of environments and use cases such as unified
communications (UC), Session Initiation Protocol (SIP)trunking, mobile and IP multimedia subsystem (IMS) networks,interworking with web real-time communications (WebRTC), andcontact centers. In this chapter, you discover the unique requirements and challenges for each of these use cases.

Unified Communications
Gone are the days when enterprise communications meant aphone on every employee’s desk. Today’s employees expect rich,seamless collaboration from almost any desktop or mobile device.
Enterprises need to harness the power of unified communications (UC) and the flexibility of bring your own device (BYOD)
policies to increase employee productivity, reduce costs, andimprove customer service.
Chief information officers (CIOs) are looking to UC and cloudbased services to meet the rising demand for real-time

CHAPTER 4 Deploying SBCs for Different Use Cases

23

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

communications, yet a common barrier to UC adoption is a lackof interoperability between the vendor-specific voice, video, andmessaging systems that exist in most enterprise networks.
While SIP was meant to break down many of those barriers, even
SIP-based systems face issues, and they often require significant interworking and transcoding to provide acceptable levels
of interoperability. Thus, most enterprises fall short of a truly
unified model of communications and collaboration, potentiallylimiting the ability of users to easily and consistently consume
rich media services.
The road to UC has been paved with wasted time and money: timespent on long service engagements and endless interoperability testing, and money spent on private branch exchange (PBX)
upgrades and new equipment. But an SBC can provide a session
management framework for UC and SIP communications thatcoordinates PBXs, room-based videoconferencing, and businesscollaboration tools across a wide variety of IP devices (smartphones, tablets, and so on), so enterprises can more easily integrate and create a true UC environment.
As you move more services and applications into the cloud, SBCbased session management unites cloud-based services with yourexisting on premises-based enterprise communications to ensure
a rich, easy-to-manage UC experience.

Enterprise Connectivity
Deployment of SBCs in enterprises is becoming more common as
businesses replace legacy PBXs and on-premises contact ­centerswith cloud-based services such as Microsoft Teams, Zoom Phone,
Cisco Webex, Genesys Cloud, Five9, NICE CXone, and dozens ofsimilar services. For an enterprise, the SBC is the first line ofdefense between its telecom provider and its cloud-based collaboration system, providing cost-effective and secure connections
across enterprise networks and branch offices.
In addition, enterprises in various industries must comply withregulatory requirements such as the U.S. Health Insurance Portability and Accountability Act (HIPAA) and industry standards
such as the Payment Card Industry’s Data Security Standards (PCI
DSS). Enterprises must maintain the highest levels of security

24

Session Border Controllers For Dummies, 7th Ribbon Special Edition

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

to protect their customers’ information and maintain regulatorycompliance.
Many companies also have branch offices and a mobile or virtual workforce that add to the requirement for reliable and securecommunications. In all these areas, the SBC has an important role.
In the enterprise, SBCs provide connectivity, ensure quality
service (QoS), perform prioritization of emergency 911 callof ­routing, enable call recording, and produce call detail records
for accounting. SBCs may also provide gateway functionality(connecting analog devices or primary rate interface [PRI]
trunks), VoIP mediation, access to public switched telephone
networks (PSTNs), and survivability features for the enterprise.
The SBC is the secure boundary between the enterprise andservice provider networks.
SBCs in the enterprise can be implemented in various deployment
options. SBCs can be hardware-based appliances or softwareonly virtualized or cloud-native solutions, enabling deployment
in a data center or in private or public clouds.

MobileReal-time communications has changed rapidly from home andoffice landline phones to widespread use of mobile smartphones.
An increasing number of homes no longer even have landline
phones, and a growing number of businesses are replacing theirlandline phones and even IP phones with mobile devices.
The proliferation of mobile devices introduces some new scalability and security challenges into a real-time communications
architecture. From a scalability standpoint, there are concerns
related to the growth of video traffic over the mobile network andthe video traffic’s volatility. There are also challenges for mobile
operators associated with the increased signaling impacts of thesedevices and associated messaging and presence applications thatare common to these devices. A design challenge for the SBC is theimpact of mobile devices on the signaling plane of the SBC. Mobile
sessions are typically shorter in duration than other device sessions, but the signaling requirements of these devices translate
into more concurrent sessions that an SBC must support.

CHAPTER 4 Deploying SBCs for Different Use Cases

25

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

In most countries, mobile data communications are handled bysystems in 4G or increasingly in 5G networks. These systems
allow for the latest in high-speed data for mobile phones andother mobile devices for streaming video, data from Internet
applications, social media, and streaming music services (such as
Pandora and Spotify).
4G and 5G networks only support IP packet switching, meaningthat network links are shared by packets from multiple communications sessions. In a 4G network, mobile industry standards
have settled on the approach of using voice over long term evolution (VoLTE) for delivering voice as a data stream within the LTE
data transmission. Similarly, in a 5G network, this same approachleverages voice over new radio (VoNR), which leverages an IP
multimedia subsystem (IMS) framework that enables voice anddata transmission.

IP Multimedia Subsystem (IMS) Networks
IMS is an integrated framework for telecommunications providers to deliver voice, video, and data using the IP protocol. VoLTE
and VoNR standards are based on using IMS for providing voiceservices over 4G and 5G networks. IMS doesn’t specify an SBC in
its architecture, but many IMS functions are already inherent in
SBCs.
SBCs are the right place to perform the following IMS functions:» Proxy-call session control function (P-CSCF): This provides
an entry point into the IMS subsystem from user endpoints.
An SBC integrates the P-CSCF with the access bordergateway function (A-BGF) to handle the media and signaling
data appropriately. The SBC provides capabilities such as
network address translation (NAT)/firewall traversal, user
identity privacy, encryption, and policy management.

» Access transfer control function (ATCF) and accesstransfer gateway (ATGW): The ATCF and ATGW functions
ensure that the handoff of the call doesn’t introduce anunacceptable interruption of media flow.

26

Session Border Controllers For Dummies, 7th Ribbon Special Edition

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

» Interconnect border control/gateway function (I-BCF/

I-BGF): Handles the signaling and media of calls. An interconnect SBC performs functions such as network topology hiding,monitoring and lawful intercept, routing of signaling into thecore of the IMS, and policy management on a per-trunk basis.

WebRTCWebRTC is a technology that allows end-users to access phone,
video, or texting capability right from a web page and also toshare screens (have multiple users see the screen of one user
at the same time). The SBC plays an important role in WebRTC,
including» Enterprise security: Because WebRTC applications run in abrowser and typically transmit application data across theInternet, a risk of attacks on enterprise servers does exist.
Consider a case in which a customer initiates a support
services call from a WebRTC-enabled web page. If an SBC isplaced between the WebRTC application server and the SIP
network at the contact center, it can secure the SIP networkin the contact center. The SBC can also provide session
control and management between the WebRTC server andthe SIP server at the contact center.

» VoIP phone calls: In this scenario, consider a VoIP call from a

WebRTC-enabled web page to a VoIP phone. The SBC provides• Security between the WebRTC application server and the
SIP network• Session control• Transcoding between, for example, Opus (the default
codec for WebRTC) and G.729 telephony protocols» PSTN phone calls: In this scenario, consider a call from a
WebRTC-enabled web page to a landline phone on a
PSTN. The SBC provides• Security between the WebRTC application server and theTDM gateway• Transcoding and internetworking between the WebRTC
application server and the TDM network

CHAPTER 4 Deploying SBCs for Different Use Cases

27

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

» Video support: Consider a WebRTC-enabled web page

initiating a video chat with a non-WebRTC-enabled IP video
phone. The SBC provides• Transcoding between the VP8 and H.264 video confer-ence codecs, the WebRTC application server, and the IP
video phone• Protocol internetworking between IPv6 and IPv4,

Real-time Transport Protocol (RTP), and Secure RTP (SRTP)
for video media transfer• QoS and policy control, ensuring that the real-time media
data get network priority» Lawful intercept: The SBC supports SIP recording (SIPRec)for lawful intercept of both signaling and media datatransferred between the WebRTC server and the destination
IP phone.

Contact Center
The contact center brings together the challenges faced by otheruse cases for SBCs. The contact center is often among the mostimportant functions a business has, and both employee and enduser expectations are high.
Due to the importance of the requirements for both security andquality of service in this crucial function, Chapter 5 is completely
dedicated to the role of SBCs in contact centers. Head over there
to find out more.

28

Session Border Controllers For Dummies, 7th Ribbon Special Edition

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

IN THIS CHAPTER»» Understanding the unique needs ofcontact centers»» Improving the contact center experience

Chapter5

Exploring theContact CenterIn this chapter, you learn how the contact center has evolved
into a critical point of, well, contact between a business and its
current and future customers. You also discover how a session
border controller (SBC) can help address the critical real-timecommunication challenges the contact center poses to anorganization.

Identifying Contact Center Needs
The contact center has evolved from a voice-only call center toan omnichannel experience where agents handle voice, email,chat, text messages, and video calls. However, as much as multichannel is the norm, voice remains the dominant channel
between agent and customer.
Regardless of the interaction channel, the contact center is vitalto the success of many businesses because it’s often the mostimportant point of interaction between a business and its current
and future customers. If agents aren’t available or the quality ofcommunications is poor for sales situations, prospects will simply

CHAPTER 5 Exploring the Contact Center

29

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

hang up and try another company. If support is needed, customers who have a poor experience are likely to form a poor opinionof the company, negatively affecting future purchases. Customers
may also create negative online reviews and say negative things
to work colleagues, friends, and family about the company andits offerings.
There are few places in businesses where the value of customer
interactions is so easy to measure. The value of a completed sale,the number of transactions per minute, and customer satisfaction metrics can all be measured and tied back to contact center
performance. It’s no wonder that organizations are willing tospend aggressively to ensure that their contact centers are always
available and offer the best experience possible.
SBCs play a crucial role in the contact center experience because
they’re the first point of entry for telecom services. First and foremost, they have to be ultra-reliable, because a failure would riska reduction in sales revenue or lower customer satisfaction. SBCs
also have to thwart telephony denial-of-service (TDoS) attacks
that try to block access by overloading the contact center withfake calls, preventing legitimate calls from getting through. SBCs
may also be called on to reroute traffic if a contact center is overloaded, or to move traffic based on time of day.

Using an SBC to Improve Efficiency
Contact center efficiency is crucial to customer experience, so
agent productivity, security, and quality control are increasingly
important. An SBC can add value in these areas:» Call recording: Contact center managers use call recording

as an evaluation and training tool to ensure that contact
center agents provide the highest level of quality in customer
service. Additionally, in certain applications, government
regulations require calls to be recorded for legal reasons andfor consumer protection.
Traditionally, call recording in communications networks wasdone by consuming an extra data port on a switch to
replicate the call data to the recording system. Consuming
an extra data port to record calls doesn’t scale well in many

30

Session Border Controllers For Dummies, 7th Ribbon Special Edition

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

contact centers that need to record each call that comes into
the system. Instead, an SBC simply replicates the call session
to send the signaling (SIP) and media (RTP) to the recording
system, providing reliable data transfer and freeing up data
ports to allow more incoming calls from customers.

» Security for remote agents: Remote or work-at-homeagents enable contact centers to be flexible and scale up or
down as business requires without the added expense of
office space and facility expansion. Consider, for example, aretailer that sees dramatically higher sales during the holiday
season. This retailer can add temporary remote agents tohandle peak demand periods. Mobile technology allows
workers to work out of their homes with flexible hours,
making this arrangement appealing to workers.
Remote agent configurations do, however, present somechallenges for the contact center. Contact centers require ascalable solution in which devices don’t need to be configured and agents don’t need to use a virtual private network(VPN; see Chapter 1). Security is also an important factor
with remote agent configurations because sensitive customer data is exchanged over the network during theseinteractions. An SBC eliminates the need for a VPN withIP phones, yet still provides the necessary security (seeChapter 1).

» Internal transfers: In many cases, calls need to be trans-ferred to a different agent in another contact center within
the organization. This can often lead to higher costs andincreased security risks if these transfers must traverse
public networks. SBCs can identify internal transfers androute the call appropriately to ensure that it stays on theprivate network, avoiding the additional costs and security
risks inherent with traversing public networks.
One case to consider is a video kiosk in a store where acustomer can make a video call to ask for assistance — acall that’s routed from a contact center to a remote agent.
In a non-SBC environment, this setup is complicatedbecause both voice and video data could travel acrossmultiple networks, requiring each border traversal to be
secured. An SBC provides the necessary security, call routing,and load balancing features to make this type of transfer
secure and cost efficient.

CHAPTER 5 Exploring the Contact Center

31

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

IN THIS CHAPTER»» Implementing intelligent routing policies»» Managing policy from one pane of glass»» Ensuring availability to critical systems»» Doing more with less (devices)»» Lowering costs

Chapter6

Determining the Valueand ROI of an SBC

You’re all hyped up. You’ve done your research, and you
know the benefits (Chapter 1) and services (Chapter 2) you
can get from a session border controller (SBC). Now it’stime to pitch the investment to your chief financial officer (CFO —who may also be known as your CF-No).
While an SBC doesn’t require a massive investment, if your CFO
sees a new line item in your budget, they’re going to want someserious justification. You need to be prepared to demonstrate thevalue of an SBC for your organization and estimate the return on
investment (ROI). In this chapter, I help you teach your CFO a newword: “Yes” — because while SBC means session border controller
to you, it’ll mean savings beyond compare to your CFO.

Reducing Costs with Intelligent Policies
The robust policy engine in an SBC enables enterprises and service providers to implement intelligent routing policies that cansave hundreds of thousands or even millions of dollars annually in

CHAPTER 6 Determining the Value and ROI of an SBC

33

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

toll charges — for example, by routing calls onto least-cost network paths, and by avoiding transferring calls to external public
networks whenever possible. An SBC can also reduce expensive
downtime and provide enhanced security for both employees andcustomers, improving metrics such as customer satisfaction andthe employer brand.
The same policy engine can move calls away from an overloaded
contact center to a back-up site or “follow the sun” so that calls
are automatically routed to the right contact center based ontime of day. Intelligent policy capabilities enable organizations to
implement policies such as» Optimized call routing» Custom dialing plans» Call blocking and screening» Emergency call routing» Local number portability lookups» Caller name delivery

Increasing Efficiency
Localized policy management in an SBC enables organizations
to efficiently manage VoIP policies at a single point in yournetwork — right at the network perimeter, where your SBC isalready securing and providing interoperability for signaling andmedia traffic. You spend less time and money managing multiple
devices such as routers, firewalls, and transcoders.
If you have a large network — or if your network grows overtime — you can further simplify policy management with a centralized policy server. In this scenario, you perform your initialconfiguration, and any future policy changes, one time and in one
place: on a primary policy server. Your changes are automatically
distributed across the network to be invoked as local policy management at all your SBCs.

34

Session Border Controllers For Dummies, 7th Ribbon Special Edition

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

FLYING HIGH WITH RIBBON SBCs
A U.S.-based, international airline maintains a global contact center
to deal with reservations, rewards programs, flight changes, seating
assignments, and other business-critical calls. The airline also
supports numerous voice applications for maintenance andsupport teams, ground support (baggage, fueling, and so on),logistics, in-cockpit and paging systems, airport ticket counters,
mobile workforce support, and even airport courtesy phones.
The airline faced functional and expense-related challenges with its
legacy telecommunications systems. Specifically, the airline needed to• Migrate its contact center to an all-IP voice infrastructure without
discarding its installed base of legacy equipment• Reduce costs• Improve employee productivity• Maintain voice security• Improve customer experience across a variety of real-timecommunications applications and devices

To solve these challenges, the legacy voice systems, which weretime-division multiplexing (TDM) private branch exchanges (PBXs)
and circuit-switched integrated services digital network (ISDN) primaryrate interface (PRI) voice circuits, were migrated to a software-based
VoIP contact center and session initiation protocol (SIP) trunking to
reduce voice costs while still allowing interworking with the installed
equipment base. At the same time, the airline was able to centralize
control of its voice communications to provide load balancing andleast-cost routing for inbound interactive voice response (IVR) callsfrom customers.
The airline installed Ribbon SBCs and a Ribbon policy and routing
server (PSX) to provide• Interoperability between legacy voice systems and SIP trunking• Centralized call control and routing• Secure access for both on-campus and remote contact center
agents and mobile employees(continued)

CHAPTER 6 Determining the Value and ROI of an SBC

35

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

(continued)

With the Ribbon solution, the airline achieved dramatic results• Reduced call costs and network operating expenses• Least-cost routing for all calls• Keeping internal calls on the airline’s internal network instead ofrouting them across a carrier’s network• Lower capital expenditures• Improved uptime and reliability for the contact center• Secure connectivity for remote workers and home-based
contact-center agents

Minimizing Costly Downtime
Downtime of business-critical systems — such as your real-timecommunications — is costly. A robust, highly available SBC is
designed with redundant configurations to eliminate single pointsof failure, providing available capacity during peak loads andseamless failover capability if a critical component fails. A welldesigned SBC architecture can recover seamlessly from faults andhas the capacity to restore its state and handle a potential flood of
VoIP client re-registrations if required.
A redundant, high-availability architecture is important regardless of whether your SBC (and other components) is hardwarebased, virtual, or cloud-native.

Consolidating Multiple Functions
Say you wanted all the features and benefits of an SBC, but you
decided to build it yourself. You’d need to cobble together various
functions of firewalls, routers, servers, gateways, and multiple
protocol stacks to individually handle all the security, SIP translation, media transcoding and transrating, and call admission
control (CAC) functions that an SBC provides. But if you consolidated all that functionality into an SBC, you’d realize significant
savings:

36

Session Border Controllers For Dummies, 7th Ribbon Special Edition

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

» Reduced capital expenditures (CAPEX): Simply put, youhave fewer things to buy, and SBCs cost less money. For
those network elements and functions that you need forother functionality, you don’t need to overbuild/over-specify
them to allow capacity for the SBC functionality that’s
handled elsewhere.

» Lower operating expenses (OPEX): You can save money

on recurring expenses such as rack space, power, andcooling with an SBC solution — whether physical, virtual,or cloud native — compared to multiple devices installed inyour data center or telecom equipment room.

Your CF-No will be itching to write you a check when you explainthat the choice of an SBC is a classic “buy or build” scenario that
reduces CAPEX, lowers OPEX, and offers greater security, lessdowntime, and enhanced functionality.

Getting Real about Cost Savings
A virtual or cloud-native SBC can save additional money by allowing your business to use common server infrastructure to scale
SBC capacity without adding proprietary hardware or requiring
significant additional rack space, power, and cooling. Virtual andcloud-native SBCs can be instantiated, provisioned, and configured via automation, providing more rapid and easier deployment
in data centers, on customer sites, or on private and public clouds.

SHOPPING FOR AN SBC SOLUTION
A U.S.-based retail chain needed to consolidate its voice management
into a centralized system while migrating from legacy circuit-switched
TDM to SIP trunking to reduce costs and to implement specificsecurity features.
The retailer’s requirements included• Saving money with SIP trunking• A centralized policy and call routing control for all stores(continued)

CHAPTER 6 Determining the Value and ROI of an SBC

37

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

(continued)• A rapid rollout, with the ability to convert all stores to SIP trunking
within a few years• Specialized routing for inbound IVR calls directed to its in-store
pharmacies (specifically, the ability to provide dial tone tothese calls)• Data security restrictions related to its pharmacy business• Maintaining security on all calls
To solve its issues, the retailer deployed a Ribbon SBC and PSX in
two data centers to provide a centralized dial plan for all stores.
The retailer leveraged Ribbon to develop an installation plan,
perform configuration, and develop and implement a test plan.
The initial deployment was successfully defined, designed, tested,
and implemented in just a few weeks. The deployment produced
the following results:• In phase 1, the retailer realized more than $500,000 in annual
savings from reduced toll fees and TDM/PRI trunk leases.

• SIP trunking enabled the retailer to buy its SIP sessions “in bulk”
and distribute those sessions flexibly across its many stores.

• The retailer connected the multi-vendor PBXs across its stores andmanaged all its dial plan and routing information in a centralized
location. Centralized dial plan management will save the retailer
hundreds of hours per week that formerly went to PBX provisioning and upgrades, enabling the retailer’s IT team to divert its internal resources to more critical, revenue-generating projects.

• It provided built-in Transport Layer Security (TLS), Secure Real-time
Transport Protocol (SRTP), and Internet Protocol Security (IPsec)
encryption with no degradation in SBC session performance.

• It provides much-needed protection against potential network

threats such as distributed denial-of-service (DDoS) attacks, which
can be particularly damaging to a large retail business during theholiday season — especially for a business that relies heavily on its
communications network for both sales and customer service.

38

Session Border Controllers For Dummies, 7th Ribbon Special Edition

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

IN THIS CHAPTER»» Improving management efficiency andperforming under pressure»» Securing the network and ensuring
customer experience»» Playing well with others and deploying in
the cloud

Chapter7

Ten Reasons to Choose
a Ribbon SBC

W

hether you’re an enterprise using Voice over Internet
Protocol (VoIP) or unified communications (UC), or aservice provider offering VoIP or UC services to yourcustomers, your choice of session border controllers (SBCs) is
integral to your real-time communications architecture and thesuccess of those services. In this chapter, you discover ten reasons
to choose a market-leading Ribbon SBC solution.

Robust Security
Securing the Session Initiation Protocol (SIP) network is a highpriority task for enterprises and service providers alike. Ribbon
SBCs are designed to» Provide end-to-end encryption on both the signaling andmedia components of network traffic.

» Hide the topology of the private portions of your networkwith a back-to-back user agent (B2BUA, see Chapter 2).

CHAPTER 7 Ten Reasons to Choose a Ribbon SBC

39

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

» Protect the network from distributed denial-of-service(DDoS) and telephony denial-of-service (TDoS) attacks while
maintaining the capability to connect legitimate sessions(Chapter 1 describes DDoS/TDoS attacks).

» Implement block lists, grey lists, and allow lists (seeChapter 1).

Peak Performance
The proliferation of applications and devices has led to an explosion in the volume of SIP traffic on enterprise and service provider
networks. Ribbon SBCs are designed to deliver peak performanceat scale, regardless of traffic load or features that are enabled.
They’ve been field-proven in Tier 1 service providers and in someof the largest enterprises in mission-critical roles, including in
demanding verticals such as financial services and healthcare.

High-Scale Transcoding
Both transcoding and transrating are computationally complex
processes — imagine what it takes to completely disassemble
and reassemble a voice in real time without inducing noticeable
latency or delay into the stream. Not all SBCs can scale transcoding for thousands of simultaneous sessions, but Ribbon’s
SBCs can scale to support high levels of transcoding without any
effect on other computational functions, such as security and calladmission control (CAC), that the SBC must also perform.

Advanced Media Support
Today’s SBCs need a robust media component that has both thecomputational horsepower and the sophisticated software to
perform on-the-fly transcoding and transrating of all sorts ofmedia. Most enterprise networks are fully converged, meaningthat they handle all voice and data traffic. The SBC is an importantcomponent for

40

Session Border Controllers For Dummies, 7th Ribbon Special Edition

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

» Securing converged networks» Providing quality of service (QoS) to ensure an outstanding
customer experience» Performing the necessary transcoding or transrating tointeroperate on all media streams

Interoperability
Different vendors and different VoIP networks may speak inslightly incompatible ways when they use SIP (see Chapter 1).
This incompatibility can result in calls that can’t be completed orthat are degraded in some way (such as missing some functionality). The SBC provides the critical role for interoperating acrossthe different variants of SIP.
Ribbon SBCs support all known variants of SIP through SIP normalization (translating between different SIP variants), either byusing static rules configured on the SBC, or on the fly as different
varieties of SIP are encountered by the SBC.

Multiple Certifications
An SBC provides interoperability with real-time communication
products from many vendors. With the rapid adoption of unified
communications as a service (UCaaS), one of the attributes to lookfor is certification from leading UCaaS providers such as Microsoft
Teams, Zoom, and Ring Central. Ribbon SBCs have been certified for Microsoft Teams Direct Routing, including media bypass
and local media optimization options. Ribbon SBCs have also beencertified for interoperability with Zoom Phone and Ring Central.
And a special note for those of you who work in the United Statesfederal government: Ribbon has certifications for U.S. government
deployment with certified compliance to the Joint Interoperability
Test Command (JITC) and Federal Information Processing Standard (FIPS) 140-2 requirements.

CHAPTER 7 Ten Reasons to Choose a Ribbon SBC

41

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

Seamless Scalability
Ribbon uses a three-dimensional approach to scalability by separating the processing functionality of the SBC so that individualtasks, such as transcoding or encryption, can scale up or down
without impacting the performance of other SBC tasks.
Ribbon divides SBC processing into three categories:» Signaling and general computing» Media processing for networking» Transcoding
With this approach, when certain functions in your VoIP networkneed more horsepower, you have it. But you don’t lose capacity inother areas that already have a comfortable degree of overhead.
Best of all, this fundamental software design works for hardware
appliances as well as virtual and cloud-native deployments.

Virtual and Cloud Native
A decade ago, Ribbon innovation introduced the industry’s leading software-based virtualized SBC with all the same features asa hardware-based SBC but architected for high availability andscalability. It ran on commercial off the shelf (COTS) platforms for
deployment in data centers as well as private and public clouds.
Ribbon innovation has now delivered the next step in SBC evolution with an industry-leading, cloud-native SBC. Optimized
to take advantage of microservices design, deployment in containers, automated life cycle management using Kubernetes, andintegration with an observability framework, Ribbon’s cloudnative SBC further extends and amplifies the attributes of highavailability, reliability, and support for new and advanced features, while delivering performance at scale.

42

Session Border Controllers For Dummies, 7th Ribbon Special Edition

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

Centralized Policy and Routing Control
In conjunction with Ribbon’s policy and routing server (PSX),
Ribbon SBCs deliver localized policy control without the overheadof separately managing policies at each SBC. Ribbon’s PSX delivers policy management in which provisioning policy and routing
data is centrally managed and policy and routing information is
automatically pushed to every SBC. Not only is this faster, but also
it’s less prone to error because changes are made once insteadof many times (potentially hundreds of times across hundreds ofsites).

Proven Track Record
SBCs perform a mission-critical role for enterprises and service
providers. As such, you want to make sure you’re working with avendor that has the experience and expertise to deliver a resilient,high-availability solution with no single point of failure. Whether
you’re deploying an SBC as an appliance, as virtualized software,or as a cloud-native solution, you want to make sure that your
SBC vendor understands what you need for success. With morethan 20 years of innovation and implementation experience,
Ribbon knows how to deliver and has the track record and customer testimonials to prove it.

CHAPTER 7 Ten Reasons to Choose a Ribbon SBC

43

These materials are © 2024 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited.

ISBN: 978-1-394-19693-7
Not For Resaledummies
A Wiley Brand

WILEY END USER LICENSE AGREEMENT
Go to www.wiley.com/go/eula to access Wiley’s ebook EULA.