The Mobile Network’s Founder and Editor, Keith Dyer, joins Syniverse’s Chief Marketing Officer, Mary Clark, and Senior Solutions Engineer, Leo Casey, this week to help mobile operators better understand the future of roaming and charging settlement for VoLTE.

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VoLTE Charging and Clearing Explained
Mary Clark – Chief Marketing Officer, Syniverse
Keith Dyer – Founder and Editor, The Mobile Network
Leo Casey – Senior Solutions Engineer, Syniverse

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#VoLTE
VoLTE is on the Rise
430 VoLTE-
capable devices
- GSA
521 operators have
commercially launched LTE
networks
with 560 forecasted by
end 2016
82operators in
43countries have
launched VoLTE
- GSMA
-GSA
146 operators are
investing in VoLTE-
related activities
- GSA
-GSMA

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#VoLTE
Already
Launched
Next 6
Months
6-12 Months
12 Months or
Beyond
Undecided
If You Are Planning to Launch VoLTE Roaming,
What is Your Timeline?

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#VoLTE
Keith Dyer, Founder and Editor, The Mobile Network
 Founded The Mobile Network in 2013, introducing a new voice to the
media covering mobile network technology
 17 years of experience covering the mobile network technology
ecosystem as a journalist and editor
 Tracked the development of the VoLTE ecosystem since the beginning
Leo Casey, Senior Solutions Engineer, Syniverse
 Responsible for supporting Syniverse’s Connected LTE, Intelligent
Roaming, MVNO, and clearing/billing services
 15+ years of project management for roaming, business analytics, and
GSM data clearing
 GSMA regional conference presenter
Today’s Expert Panelists

5. VOLTE Roaming: charging
Keith Dyer, Editor, The Mobile Network
www.the-mobile-network.com
keith@the-mobile-network.com
Twitter: @keithdyer
#VoLTE

6. #VoLTE

7. Recap on the story so far
Underlying technical choices:
Home Routing (S8HR)
Easier but some features lacking or challenging:
e.g. lawful intercept, emergency call, SRVCC
Local Breakout (LBO)
Technically more challenging, but more complete
operator control
#VoLTE

8. Choices: impact on charging
Underlying technical choices: impact on charging
Home Routing (S8HR)
Can only rate on per kb consumed by voice call
If call drops or falls back - what then?
Local Breakout (LBO)
Signalling changes between home and visited gateways
Keeps current charging model, esp for inbound
Architecture = Charging Capability = Business Model Impact
#VoLTE

9. What are operators thinking? 1/2
Roaming architecture choices:
Home Routing (S8HR) Clear favourite for early movers so far, but some do NOT
like & Local Breakout (LBO) has support for future.
“Only LBO will allow us to meet regulatory, business and customer experience
expectations… We have started to test LBO Home routed architecture with no
significant network issues.” (Operator “A”)
“LBO has been trialled and failed by a few operators. Another major network
has specifically asked us to implement S8HR so that’s what we’re going to do as
part of this request. Ultimately we’ll probably need to support this and then in
the future enable LBO as well” (Operator “B”)
#VoLTE

10. What are operators thinking? 2/2
...about how charging and clearing will work for VoLTE Roaming?
“We’ll make it work” vs “Is it worth the hassle”
“At the wholesale level, both LBO and
S8HR allow charging and settlement
based on current contracts.”
“LBO allows consistent charging for
customers on all technologies while
S8HR will require enhancements from
both IMS and EPC networks to allow
this consistent charging.”
“S8HR will probably result in significant
decrease of value without changing
current charging principles.”
“There is tons of work involved in enabling
S8HR Outbound Roaming in order to do
Customer Charging correctly”
“It’s impossible to relate volume to minutes
or data CDRs to a call duration.”
“S8HR: Offers virtually no advantage over
a CS voice call but gives many
disadvantages.”
#VoLTE

11. EU roam like home?
Is there any impact of EU roam like home regulations
on charging methodology?
NO!
● No anticipated difference in terms of actual way billing is
done. Still need to identify session/call and charge/settle
accordingly.
“None of the main VoLTE aspects are expected to change
as a result of new EU regulation.”
#VoLTE

12. Conclusions
Still split but if pressed S8HR now (no choice due to
commercial relations) and LBO later
Operators not totally uniform on how choice impacts charging
Access to required charging data also seen as challenge
Knock-on impact is on business models
Time to understand implications is NOW
#VoLTE

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#VoLTE
S8HR LBO Hybrid
Undecided
I don’t
know
If You Are Planning to Launch VoLTE Roaming,
What Roaming Architecture Do You Plan to
Implement ?

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#VoLTE
VoLTE Charging and Clearing Explained
Evolution towards
All-IP/IMS
New and Legacy
Network Technologies
Technical and
Process Changes
for Charging
VoLTE Charging
and Clearing
Principles
Different VoLTE
Implementations
S8HR and LBO

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#VoLTE
Evolution of TAP Events
CS TAP CDRs
 Mobile Originating Call MOC
Event for Voice and SMS-MO
(only used for 2G , 3G Traffic)
 Mobile Terminating Call (MTC)
Event for Voice and SMS-MT
(only used for 2G , 3G Traffic)
 Supplementary Service (SS)
Event in association with Voice
Service
GPRS TAP CDR
 GPRS Event for data bearer
stream (2G , 3G , LTE Traffic)
VoLTE TAP CDRs
 Mobile Session – MSESS
(only used for Voice Traffic
over LTE)
 Messaging Event – MSG
(only used for SMS Traffic
over LTE )
2G – 3G 4G

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#VoLTE
 A single VoLTE call must be represented in a single
Mobile Session (MSESS) TAP Call Detail Record (CDR) in
the same manner like the case with Voice over Circuit
Switch (CS). It is not allowed to present partial VoLTE
Calls separately on TAP.
 VoLTE Traffic is not allowed to be represented in CS
MOC and CS MTC Events on TAP
 CS Voice and SMS Events are not allowed to be
represented in MSESS and MSG Events on TAP
 VoLTE S8HR is volume based charging data service:
 Using the existing GPRS call record in TAP
 Charges can be differentiated by QoS Class Identifier
(QCI) and also by APN as any other data usage
 Signaling (QCI5) can also be separated from payload
traffic (except for SMS)
 VoLTE has been supported since TAP3.12,
May 1, 2012
VoLTE Principles

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VoLTE Support in TAP

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#VoLTE
TAP for Voice Over LTE
 TAP support for LTE/IMS (TAP3.12)
 Two new TAP records for VoLTE
 Messaging event (MSG)
 Mobile session (MSESS)
 New TAP fields in two new records
 New type of roamer
 New type of destination
 New recording entity code/type:
9:P-CSCF
Technical and Process Changes
for Charging
TAP Challenges for VoLTE
 No single network element will
contain all charging elements
 Correlation of data from
SGSN/S-GW/P-CSCF
 CDRs via common Charging ID
 Charging ID available from P-CSCF
to identify each unique call
 Not all “usual” TAP information
readily available
 Charging only for service and not
for service + bearer (may not be
straightforward)

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#VoLTE
Voice and SMS in CS vs. LTE
Item CS LTE
User Identities
IMSI
MSISDN
IMSI complimentary with Private User ID
Public User ID
Origination /
Destination
E.164 Number E.164 Number , SIP URI, Tel URI
CDR Source MSC SGSN , S-GW , P-GW , P-CSCF, ATCF, TRF
CDR Correlation Not Required
Required by using the Charging ID present in the EPC
& IMS Domain
CDR Unique
Identifier
Call Reference &
SMS Reference
IMS Charging Identifier
TAP Record
MOC /MTC
SMS-MO/SMS-MT
MSESS + Messaging Service
MSG +Messaging Event Service
GPRS(S8HR)

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VoLTE (S8HR) Home Routed

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VoLTE (S8HR) Home Routed Architecture
Advantages
 S-GW is the main source for charging information
 Basic bearer data volume charging
 No technical complexity where handovers are not involved
 QCI mechanism is used to identify VoLTE calls
 TAP Charging capabilities are already present
 CAPEX/OPEX is low for wholesale billing
Challenges
 Non-granular mechanism to charge and identify single
VoLTE calls
 No service awareness for services used on the VPMN side
 Aggregation/Charging for VoLTE handover scenarios with
3G/4G are complex
 Duration-based charging for VoLTE will be complicated
 Correlation of charging information between VPMN and
HPMN is difficult
IPX
IPX
E-UTRAN
MME
VPMN A-Party HPMN A-Party
B-Party
HSS
P-CSCF
S-CSCF
TAS
SGW
DRA
IBCF
VoLTE
Roaming
Interconnect
IMS
IMS
Exchange
PCRF
PGW

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#VoLTE
LTE Data Bearers – S8 Home Routing
QCI = 5
QCI = 1
QCI = 2 Video Media - Dedicated Bearer
Application Servers
IMSAPN
LTE Bit
Pipe
Voice Media - Dedicated Bearer AS
AS
IMS
HPMN
Signaling - Default Bearer
QCI Values TAP Values
Value
QCI
Priority Description
CTL2
Value
Record
Type
APN
1 2 Conversational Voice 21 GPRS IMS
2 4 Conversational Video (Live Streaming) 22 GPRS IMS
5 1 IMS Signaling (Voice, Video, SMS) 25 GPRS IMS
PDN-GW
S-GW
VPMN

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#VoLTE
 Signaling and media anchored in
home network
 No IMS accounting records sent
from visited to home network
 Records generated in home network
 IMS accounting records not available
on visited network
 Visited network only has visibility
into bearer accounting
 QoS, bearer usage
 TAP billing records sent to clearing
house for bearer data usage
 No change from GPRS settlement
process however the VPMN may
decide to differentiate charging
based on QCI values
Accounting Flow S8 Home Routing
Billing
Domain
Billing
Domain
Access
Network
Visited
Network
Home
Network
Clearing
House
Bearer
Accounting
Offline
Charging
System
S-GW PDN-GW
Offline
Charging
System
Online
Charging
System
(Prepaid)
IMS Accounting
TAP
P/I/S-CSCF
IMS

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VoLTE (LBO)

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VoLTE (LBO) Local Breakout Architecture
IPX
IPX
xCSCF
MME
VPMN A-Party HPMN A-Party
B-Party
HSS
P-CSCF
S-CSCF
TAS
IBCF
DRA
IBCF
VoLTE
Roaming
VoLTE
Interconnect
EPC
IMS
IMS
IMS
Exchange
IMS
Exchange
PCRF
IBCF
Advantages
 More visibility into the control and media plane aspects of a
call or video session as it’s taking place with IMS
 Full support for lawful intercept and emergency call handling
 SRVCC support continuity of a voice call when moving between
LTE and CS networks
 VPMN has visibility of the call information using their IMS
records, TAP records can be created to reflect MOUs. This
makes it possible to use TAP for retail billing
Challenges
 More complexity implementing and supporting VoLTE roaming
 Interoperability issues that must be resolved between IMS cores
 Requires multiple feeds from many network elements for both
visited and home operators
 Operators may choose to implement home routing for data, but
local breakout for voice, adding complexity
 The TAP 3.12 MSESS & MSG records need to be supported by
both roaming partners

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LBO Roaming Scenarios
VPMN Routed HPMN Routed
TAP Event Network Source
MSESS CDR TRF Network CDR
TAS
S-CSCF
Destination
TrGW
VPMN
HSS
IBCF
IBCF
TRF
IC Provider
IC Provider
IBCF
P-CSCF
PGW
IC Provider Control
Media
TAS
S-CSCF
Destination
TrGW
VPMN
HSS
IC Provider
IC Provider
IBCF
P-CSCF
PGW
IC Provider
Control
Media
HPMN HPMN
TrGW
IBCF
IBCF
TAP Event Network Source
MSESS CDR P-CSCF Network CDR

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#VoLTE
VoLTE Call – MSESS TAP CDR
General
APN
IMS Domain
ATCF Network CDR
Called Number Address
Subscription ID
IMS Charging Identifier (ICID 1)
Service 1 (Voice)
Media Component 1
Charging ID 1
Service 2 (Video)
Media Component 2
Charging ID 2
IMS APN
PDP Context 3 (Internet Access) – Charging ID 3
PDP Context 2 (Video) – Charging ID 2 – (ICID 1)
PDP Context 1 (Voice) – Charging ID 1 – (ICID 1)
S-GW P-GW
LTE EPC Core
External Packet Data Network
TAP MSESS CDR
IMSI
MSISDN
Location Info.

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#VoLTE
 Bearer accounting records optionally sent from visited to home network
 IMS accounting records generated by visited P-CSCF and home S-CSCF
 Diameter interfaces to offline and online charging systems
 TAP billing records may be sent to clearing house to support legacy settlement and retail billing processes
 IPX provider has access to IMS accounting records
LTE Accounting Flow Local Breakout
IMS Services
Visited Network Home Network
TAP
IMS IMS
Bearer
Bearer Accounting
IMS Accounting
IPX
Proxy
IPX
Provider
Offline/Online
Charging System
Billing
Domain
Access
Network
Clearing
House
PDN-GW
Billing
Domain
Offline
Charging
System
S-GW
P-CSCF I/S-CSCF

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#VoLTE
 LTE and the evolution to an all IP-based
network represents new challenges and new
opportunities
 TAP has evolved to support VoLTE roaming, but
not all TAP records are being used at this time
 Multiple network routing scenarios bring
different advantages and challenges to
charging and clearing
 S8HR is most widely used VoLTE routing
scenario in use today
 While the information is not as granular for
wholesale charging and clearing, options are
available to identify and charge for it
 Roaming and financial teams need to work
closely with their network engineering teams
to understand which routing scenarios they’re
using and what information is available to
them for charging and clearing
Webinar Recap
VoLTE charging and clearing can be complex, but not impossible.

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Q&A

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Thank You!
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