This document discusses monitoring voice quality in VoIP networks using Session Border Controllers (SBCs). SBCs are placed at the border of voice networks and can measure metrics like latency, packet loss, and jitter to calculate Mean Opinion Scores (MOS) for calls in real-time. SBCs can record these metrics in call detail records and analyze patterns over time to isolate potential causes of poor voice quality like network congestion or specific carriers. The document provides an example use case where an SBC routes calls dynamically based on recent MOS scores of different carriers to ensure the best voice quality for customers.

2. Video Library on YouTube
• ProSBC Training Modules
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• How-to Tutorials
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2
youtube.com/telcobridges

3. 3
Introductions
Alan D Percy
Chief Marketing Officer
alan.percy@telcobridges.com
@AlanDPercy
Luc Morissette
Director of Customer Support
luc.morissette@telcobridges.com

4. TelcoBridges Inc.
• Manufacturer of VoIP gateways, signaling
gateways, and SBC software for carriers and
enterprises
• Employee Owned
• Founded in 2002
• Employees: ~40
• Headquarters: Montreal, Canada
• Hardware & software R&D as well as
production of its products in Montreal
• Sales/Support offices:
Montreal, Turkey, Hong Kong
• 24/7 technical support
4
TelcoBridges HQ

5. 5
Agenda
• Voice quality and the
customer experience
• Causes of poor voice quality
• Measuring voice quality on-the-fly
• The role of SBCs in monitoring voice quality
• Isolating voice quality issues
• Use Case example
• Your Questions
A
D
N
E
G
A

6. VoIP Voice Quality
Voice Quality
&
The Customer Experience
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7. 7
Troubles in Paradise!
https://www.thesipschool.com/files/The-SIP-Survey-2018.pdf

8. The Customer Experience
Poor voice quality:
• Increases errors
• Slows agent handling
of calls
• Causes stress
• Harms customer
satisfaction
8

9. VoIP Voice Quality
Voice Quality
Background
9

10. 10
Common VoIP Impairments
7 6 5 4 3 2 1
No impairments
7 6 X X 3 2 1
Packet Loss
6 5 4 3 2 1
Jitter
5 4 3 2 1
Latency
Delay
RTP Packets (voice payload)

11. 11
Other VoIP Impairments
CODEC
Mis-match
Echo
One-way
Audio
DTMF
Transport

12. VoIP Voice Quality
Measuring
Voice Quality
12

13. MOS Score - Subjective
• Defined by ITU-T Rec. P.800
• Mean Opinion Score
• A measurement of how
humans perceive speech
• Subjective testing requires 60
listeners to score the speech
• Not practical for real-time
telecommunications systems
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From EEtimes:
https://www.eetimes.com/intro-to-voip-quality-measurements/

14. 14
MOS Score - Objective
• Defined by ITU P.863
• Compares reference input
with degraded output
• Excellent predictor of
subjective MOS
• No humans required!
• Lab environments
• Not practical for real-time
telecommunications systems

15. R Factor
• R Factor is based on E-Model
• R0 = Signal-to-noise Ratio
• Is = Simultaneous impairments
• Id = delay and echo impairments
• Ie_ef = CODEC impairments
• A = User toleration of impairments
• R Factor ranges from 0 to 100
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16. MOS “on-the-fly”
16
Latency
Packet Loss
Jitter
MOS
Score
Mapping
R Factor MOS Score
CODEC
E-Model

17. 17
TelcoBridges MOS Scoring

18. VoIP Voice Quality
The Role of SBCs in
Monitoring
Voice Quality
18

19. Session Border Controllers
• The “border” of a voice network
• Point of demarcation between
carriers & enterprises
• An ideal place to measure,
track and report voice quality
issues
19

20. What can an SBC do?
20
SBC
Service Provider “A” Service Provider “B”
Measure RTP
Measure RTP
RTP
RTP
Collect RTCP
Collect RTCP

21. SBCs – Reporting Voice Quality
21
ProSBC Call Trace

22. SBCs – Reporting Voice Quality
22
https://docs.telcobridges.com/tbwiki/Toolpack:RADIUS_CDR_attributes_D
ProSBC reports MOS Score in Call Detail Records

23. 23
SBCs – Reporting Voice Quality
2020-12-09 20:16:59.936+0100,END,SessionId='a440ab1b
00000000 02005ce0
5fd1229c',LegId='0xA440AB1B',StartTime='1607541404',Connected
Time='1607541404',EndTime='1607541419',FreedTime='160754141
9',Duration='16',TerminationCause='NORMAL_CALL_CLEARING',T
erminationSource='TermInd',Calling='1200',Called='1001',NAP='NA
P_WEBINAR_A5_PRIV',Direction='answer',Media='PCMU@192.16
8.102.192:20142',Rtp:Rx='(743;0;0;0;4.3)',Rtp:Tx='(741;0;0;0;0.0)',T
38:Rx='(0;0;0)',T38:Tx='(0;0)',Error:FromNetwork='(-;-;-;-;-
)',Error:ToNetwork='(-)',MOS='4.3','0.0',NetworkQuality='100','0'
ProSBC CDR Example

24. VoIP Voice Quality
Isolating/Reducing
Voice Quality
Issues
24

25. Isolating Voice Quality Issues
• Narrow down potential sources
of imparements
• Carrier dependent?
• LAN/WAN segments?
• Time of Day dependent?
• Did something change?
• You will need a tool to analyze
and look for patterns
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26. Ways to Improve Voice Quality
26
Poor MOS
Time of Day
Network
Congestion?
Add WAN Capacity
Alternate Carrier
Voice Compression to
reduce congestion
Symptom Potential Cause Remedies

27. Ways to Improve Voice Quality
27
One-Way Voice
ALG or Firewall?
NAT?
Check configuration
Bypass ALG/Firewall
Port Forwarding
Symptom Potential Cause Remedies

28. Ways to Improve Voice Quality
28
Low MOS
Scores
Service Provider
Congestion
Reroute Traffic
Report to Service
Provider
Change Service Provider
Symptom Potential Cause Remedies

29. Ways to Improve Voice Quality
29
Echo Endpoint acoustic echo Endpoint configuration
Change endpoint
Symptom Potential Cause Remedies

30. VoIP Voice Quality
Use Case
Example of
Voice Quality
Monitoring
30

31. Use Case Example
31
Voice
Call Center Agent
Voice
Landline
Mobile
SMS
Carrier
Services
Voice
Voice Carriers
Voice
Call Center
Voice
Applications
SMS SMS
Voice & SMS

32. 32
• Challenge:
• Offer the highest quality voice quality to their customers
• Monitor their service providers to ensure they meet quality goals
• Means to redirect traffic if quality degrades
• Solution:
• Use MOS scoring features of ProSBC
• Record and analyze quality performance
• Use SBC routing priorities to adjust on the fly

33. 33
Routing on Voice Quality
SBC
Route
Script
Carrier A
Carrier B
Carrier C
Incoming Call
Route based on:
• Called/Calling Number
• Carrier availability
• Recent MOS score of carrier
• Round-robin

34. Voice Quality Analysis
34
Call Detail
Records
Update
Route
Tables

35. Enabling the Migration to
Cloud Communications
35
www.telcobridges.com
www.prosbc.com
sales@telcobridges.com
Youtube.com/telcobridges

36. View the Full-Length Video at:
www2.telcobridges.com/videolibrary
36