Over the last 12 months we’ve shared a lot of information about session border controllers, applications for SBCs, customer use cases, along with details on FreeSBC installation and configuration. During that time, also been asked dozens of questions and done our best to answer every single one of them live during the event or in writing on the TelcoBridges forum. With this milestone, we thought it was time to look back at the most popular and frequent questions. So join us as we review our “Top 10” FAQ. A recording of the webinar can be found at: https://www2.telcobridges.com/FreeSBCVideoLibrary Learn more at: www.freesbc.com

2. SBC – Top 10 FAQ
We answer your most frequently asked
Session Border Controller questions
January 2019
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3. 3
Past Webinars
http://www2.telcobridges.com/FreeSBCVideoLibrary

4. 4
Frequently Asked Questions
1. What's difference between an SBC and a SIP Proxy?
2. How does an SBC detect and defend against
DOS/DDOS attacks?
3. Can an SBC help stop Robocallers?
4. How do SBCs limit call traffic?
5. What is topology hiding? Why do you need it?
6. Can I use an SBC to perform load balancing?
7. Do SBCs facilitate billing?
8. Does FreeSBC work with ________ ?
9. What are the risks/rewards for putting SBCs in the
cloud?
10. Is FreeSBC really Free? When is it not free?

5. 5
Today’s Presenters:
Alan D Percy
Senior Director of Product Marketing
alan.percy@telcobridges.com
Marc St-Onge
Director of Sales Support
marc.stonge@telcobridges.com

6. 6
The SIP School

7. What's difference between an SBC and a SIP Proxy?
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SIP Proxy/Server Architecture
Header ManipulationRouting Engine
Media
SIP
Session
s
Public
WAN
34.0.0.
1
SIP Proxy/Server
SIP
Application
s
34.0.0.X

9. Routing Engine
Media
Media
Engine
SIP
Session
s
B2BUA
UAS UAC
Private LAN
192.168.0.X
Public WAN
34.0.0.1
Session Border Controller
SIP
Applicatio
ns
Session Border Controller Architecture

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Comparison Summary
Function Firewall SIP Server SBC
Layer 2-4 Packet Filtering   
Router / NAT / DHCP   
Prevent DOS / DDOS Attacks   
SIP Header Manipulation / Interoperability  
SIP Routing  
Toll Fraud Protection  
Topology Hiding 
Block Robocallers (STIR/SHAKEN) 
QOS Measurement / Reporting 
Media Transcoding / Transcryption 
Prevent Media Flood Attacks 

11. How does an SBC detect and defend against
DOS/DDOS attacks?
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12. DOS/DDOS Attacks
Network
Border
Internet SBC
Application
DOS/DDOS and Registration Floods

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Protecting against DOS/DDOS
• Built-in Firewall with Access Control Lists (ACL)
• Dynamic Firewall Management
• Blacklists - IP addresses/ports of known offenders
• Whitelists - known valid users
• Bandwidth Management
• Call Rate Limiting
• CPS limits, deflecting bad traffic
• Line Rate Speed Processing – Important

14. Can an SBC help stop Robocallers?
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15. SHAKEN: Verify valid calling numbers
15
Robocaller Terminating
TSP
Call with
fake caller
ID
Happy customers
Authenticate
caller ID and
sign call
Verify
signature and
apply policies
Complete
with
warning
Block
Phone Captcha
Divert
Originating
Telecom
Service
Provider
Policy
choices

16. Originating service provider authenticates
16
Session
Border
Controller
Originating Telecom Service
Provider
Authentication
Service (AS)
Secure Key
Store (SKS)
Calling Party
1. Call
originates
2. SBC sends SIP
INVITE to AS
3. AS checks caller ID, and returns
signed SIP Identity header.
4. Sends call
Outbound Call

17. Terminating service provider verifies
17
Session
Border
Controller
Terminating Telecom Service Provider
Verification
Service (VS)
Certificate
Repository
(CR)
Inbound Call
1. Call
arrives
2. Call Control initiates
terminating trigger,
sends to VS.
3. VS looks up CR URL, fetches certificate and extracts public
key to verify the signature. Uses verification and token info to
select policy and return the call to Call Control.
4. Call
terminates
Called Party

18. Coming Attraction:
18
https://www2.telcobridges.com/STIRSHAKEN201

19. How do SBCs limit call traffic?
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20. 20
Call Rate Limiting
Intelligent “Speed Limiter” managing
the incoming call flow
• Maximum # Calls
• Max Calls Per Second (CPS)
• Inbound and Outbound
• Handling Excess Traffic:
• “Congestion” – Slowing responses
• “Network Limit” – Configured per network
• “Hard Limit” – Reject any new requests

21. What is topology hiding? Why do you need it?
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Topology Hiding
Not exposing the
internal network
configuration or IP
addresses to the
outside world
Only the SBC is
visible to the outside
world
Substitutes IP
addresses in SIP
headers and on RTP

23. Can I use an SBC to perform load balancing?
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24. 24
Load Balancing
Distributing call traffic
based on:
• Priority
• Availability
• Round-robin
• Dialed or Calling #
• Table/Script bases
• And more…
Routing Engine

25. Do SBCs facilitate billing?
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Billing Systems and SBCs
SBC
Subscribers
Call
Servers
Billing
System
$$$Text CDR
or RADIUS

27. Does FreeSBC work with ________ ?
27

28. Interoperability

29. What are the risks/rewards for putting SBCs in the
cloud?
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30. 30
SBC Deployment Models Compared
Appliance
(Bare Metal)
Virtualized Cloud
Highest Performance
Most predictable
Small CPE appliances
Dedicated hardware
Best for large scale and
private datacenter
1+1 Redundancy
Flexible deployment
options
“Service Chain”
VM overhead limits
performance and
predictability
“Pay as you grow”
CAUTION: Media
charges and throughput
caps
“Noisy Neighbors?”
Good for dynamic
requirements and
flexible deployments

31. Is FreeSBC really Free? When is it not free?
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FreeSBC Editions
Feature/Capability FreeSBC FreeSBC PRO
Back to Back User Agent (B2BUA)  
DDOS / DOS Protection  
NAT Traversal  
SIP Header / Digit Manipulation  
Call Routing  
Call Rate / Bandwidth Limiting  
Access to Wiki and Community Support  
Live Support and Software Update Service 
High Availability 1+1 90-day Trial 
Media Bypass (RTP no anchoring) 90-day Trial 
TB analytics 90-day Trial 
OSS/BSS, RADIUS, SNMP & API Connectors 90-day Trial 
For a full comparison, see: www.freesbc.com/pricing

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Learn more at: www.FreeSBC.com

34. 34
Learn More…

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Q&A
The SIP School
www.thesipschool.com
Free copy of SBC software:
www.freesbc.com
Other Recorded webinars at:
freesbc.com/video-library
Q/A?