VoLTE allows operators to provide voice services over LTE networks using IP Multimedia Subsystem (IMS) technology. This provides several advantages over existing solutions like Circuit Switched Fallback (CSFB) including higher voice quality, network capacity and efficiency gains, and an improved user experience with faster call setup times. Operators are deploying VoLTE to transition to all-IP networks and offer voice and multimedia services like video calling over their LTE infrastructure using IMS.

1. VoLTE
bringing you closer

2. CONTENTS
Why do We Need LTE Voice Solution
Challenge from OTT
CSFB
VoLTE
VoLTE Advantages

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Why do We Need LTE Voice Solution?
Voice is still the
main source of
income
NO CS network
in LTE
VoLT
E
3
VoLT
E
SRVCC
2
VoLT
E
CSFB
1
OTT challenge

4. 4
Secret▲
© ZTE All rights reserved
Verizon: 700M for wide coverage, transition from SvLTE to VoLTE, LTE-only terminal subsidy from 2014
KDDI: LTE 1.5G/2.1G/800M, CSFB, VoLTE (on 800M by KDDI sub-brand au)
Sprint: LTE 800/1900, VoLTE beared on 800M, CSFB also deployed
China Mobile: CSFB to 900M GSM, VoLTE deployed with SRVCC
The Voice Strategies by Top Operators
IMS VoLTE
CSFB
VoLTE
+SRVCC
CS
SvLTE
Voice beared on CS Voice beared on IMS

5. © ZTE Corporation. All rights reserved.
Challenge
from OTT

6. © ZTE Corporation. All rights reserved.
OTT is popular now
VoIP
Video-callings
Messaging services
20%+ calls through Skype in USA
40%+ subscribers use Facetime for video calls
4.38 Hundred Million, 71.4% Market Share

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The impact on operator
Voice & message
64%
Data
36% Voice: 0.3%
Message: 20.2%
Data: 98.6%

8. © ZTE Corporation. All rights reserved.
OTT put great pressure to operators…

9. CSFB
First step in LTE era,
you just need

10. 10
Secret▲
© ZTE All rights reserved
CSFB Application Scenario
Low LTE terminal penetration
rate
LTE terminals don’t support
VoLTE/SRVCC
Low quality requirement
Lack of LTE seamless
coverage
Seamless 2G/3G network
CS network doesn’t have
capacity bottleneck
User
CSFB
No IMS deployment
Operator

11. 11
Secret▲
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What is CSFB?
Circuit Switched Fallback (CSFB)
MSCs
MGW
GERAN/UTR
AN
SAE-GW
MME
LTE
Voice
Packet Data
Register
SGs
Voice Packet Data
Register
CSFB Type Description
R8 Re-direction The eNodeB brings 2/3G frequency point in the command RRC
ConnectionRelease, and then the UE can set up the CS voice directly in the
dedicated frequency point.
R9 Re-direction The eNodeB brings 2/3G frequency point and target cell’s SI message in the
command RRC ConnectionRelease, and then the UE can set up the CS voice
directly in the dedicated frequency point.
PS HO LTE switches the UE to the 2/3G for the data bearing, and then the UE
initiates the voice in the 2/3G CS domain.
CCO without NACC
(GSM only)
The eNodeB brings GSM frequency point in the command Cell Change Order,
and then the UE can set up the CS voice directly in the dedicated frequency
point.
CCO with NACC (GSM
only)
The difference is that the NACC (RIM) procedure is added. The eNodeB
triggers the NACC procedure to obtain the GERAN system information and
store it locally before it determines to initiate the CCO procedure.

12. 12
Secret▲
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Little Impact on the Legacy Network
Element Upgrade Requirement
MSC Software update. The MSC must support SGs interface.
MME (SGSN)
Software update. The MME must support the information interaction between
SGs and S3 interface.
eNodeB Software update. CSFB function should be supported.
UE
Software update. CSFB function should be supported, such as EPS/IMSI attach,
SMS processing, CS paging.
Coverage with 2/3G LTE coverage must overlap with 2/3G.

13. Here and now
you just need
Voice Over LTE
VoLTE

14. © ZTE Corporation. All rights reserved.
Voice technology development
SVLTE CSFB eSRVCC VoLTE
2G/3G LTE
2/3G CS EPC
PSTN/PL
MN
INTERNETT
Terminal
Voice
Data
LTE
EPC
INTERNET
Terminal
Voice
Data
IMS
2G/3G LTE
2/3G CS EPC
PSTN/PL
MN
INTERNET
Terminal
S
Gs
Voice
Data
2G/3G LTE
2/3G CS EPC
PSTN/PL
MN
INTERNET
Terminal
S
v
Voice
Data
IMS
No LTE seamless coverage, LTE overlap with 2/3G LTE seamless coverage

15. © ZTE Corporation. All rights reserved.
VoLTE solution
VoLTE
LTE
EPC
INTERNET
Terminal
Voice
Data
IMS
LTE seamless coverage
 Software upgrade on
the legacy 2/3G networks
 Introduce IMS system
 Very clear
 HD Voice calling
 Shortest latency,0.5s+
 Hopeful handsets
 145+ models released
Deployment
Experience
Ecosystem

16. 16
Secret▲
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SRVCC application scenario
SRVCC capable terminals
High quality requirement
users
Simultaneous Voice and
data services requirements
Lack of LTE seamless
coverage
Better coverage by 2G/3G
network
EPC supports the function
User
SRVCC
VoLTE based on IMS already
deployed
Operator

17. 17
Secret▲
© ZTE All rights reserved
VoLTE Application Scenario
VoLTE capable terminals
High quality requirement
users
Simultaneous Voice and
data services requirements
LTE continuous
coverage
IMS deployment
Backhaul has low latency
User
VoLTE
CS network has capacity
bottleneck
Operator

18. 18
Secret▲
© ZTE All rights reserved
• Converged HLR、EPC HSS
IMS HSS
LTE Handset
LTE Handset
SRVCC/eSRVCC
HLR/EPCHSS/ IMSHSS
LTE CG
BSC
Iu-PS
A
CS
Mc
IMSSv
I/S-CSCF
SCC AS MMTEL AS
• Support SRVCC/eSRVCC
trigger
• Support relevant features including
robust header compression (RoHC),
semi-persistent scheduling (SPS),TTI
bundling and eSRVCC.
• Support Sv interface
•Support SRVCC/eSRVCC • Support
SRVCC/eSRVCC
• Introduce
ATCF/ATGW to
Anchor in signaling
/Media plane
• Support Sv interface
•Support
SRVCC/eSRVCC
eMSC
MSC serverMGW
S/P-GW
PCRF
P-CSCF/SBC/ATCF/ATGW
Functional requirements for VoLTE/eSRVCC
MME
• Discover P-
CSCF/A-SBC
•Guarantee QoS by
interworking with
via the Rx interface
eNodeB PS

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VoLTE
advantages

20. © ZTE Corporation. All rights reserved.
VoLTE
advantages
Great Capacity, High Efficiency
LTE
WCDMA
GSM
 6~7 times than GSM
 2 times than WCDMA
 Save 70% invest!

21. © ZTE Corporation. All rights reserved.
VoLTE
advantages
Highest Experience
2/3G OTT CsFB VoLTE
HD-Voice
Coding
8K,
300~3400
Hz
8K,
300~3400H
z
8K,
300~3400H
z
16K,
50~7000Hz
MOS 2.3 2.3 2.3 4
Video Coding
QCIF,
176*144/
15fps
VGA,
640*480/3
0fps
QCIF,
176*144/1
5fps
HD,
720p/30fps
Call setup
time
3-5s
>5s,always
e failure
5-8s 0.5-2s

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VoLTE
advantages
All-IP architecture
PS
BSC
DataVoice
CS
NodeB
IMS
EPS
eNodeB
Voice+ RCS
Data
2/3G 4G

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VoLTE
advantages
Lower Resource usage
 Skype occupies 13 times
more throughput than VoLTE
 Battery life is 56%~89%
longer when using VoLTE
than Skype

24. © ZTE Corporation. All rights reserved.
Who can provide the most
satisfactory user experience?
1
2
3
4
5
QoS measures in place
Handover mechanism to the circuit-switched network
Interoperability between different OTT services and devices
Guaranteed emergency support measure
Strong security measures.

25. © ZTE Corporation. All rights reserved.
ZTE Voice Solution
End to end solution Powerful customization Deployment experience
• Providing all LTE network elements
• No IOT testing is needed with voice solutions
• Short time to market and cost saving
• Customized devices
• Customized features
• Customized equipments
• CMCC, CMHK, Softbank, CSL etc.
• Helping operators to enhance the
deployment efficiency.

26. © ZTE Corporation. All rights reserved.
ZTE VoLTE ，bringing you closer