4_call flow.pdf

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2015 © Samsung Electronics 1


Call Flow

4rth

February 2015


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Network Architecture


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2015 © Samsung Electronics 42015 © Samsung Electronics 4

ENB – Interface and Protocol

The Protocols that run between UE and

eNB are called Access Stratum Protocols or

AS Protocols

The Protocols that run between UE and

Core Network are called as NAS Protocolsor Non Access Stratum Protocols


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MME – Interface and Protocol


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MME – Interface and Protocol


7/1132015 © Samsung Electronics 72015 © Samsung Electronics 7

SAE GW – Interface and Protocol



SAE GW – Interface and Protocol

• IP Packet is tunneled between P GW and UE using GPRS Tunneling Protocol GTP

• Each Bearer has associated QCI

• Each QCI has GBR/ Non GBR, Priority, packet delay , Packet Error Rate defined

• PCRF decides the Bearer Type

•P GW performs the DHCP functionality = allocates IP addresses to each UE



VoLTE – Logical ArchitectureENUM – Electronic Number Mapping System

To translate a telephone number into IP address



VoLTE – Logical Architecture



RJIL Network Overview


12/11312Samsung Confidential and Proprietary Information. All Contents Copyright ⓒ 2011 Samsung Electronics Co., Ltd.

LTE reference model

NODE DESCRIPTIONS

eNB Radio interfaces and radio resource management.

Radio bearer control/radio admission control/scheduling of uplink & downlink/

IP header compression and encryption of the user plane data/eNB handover(X2)/pooling

between MMEs and eNBs(S1, many-to-many relations)

MME LTE related control plane signaling

Mobility and security functions for devices attaching over the LTE RAN/Management of all theterminals in idle mode including Tracking Area management and paging.

S-GW Anchoring point for intra-LTE and between GSM/GPRS, WCDMA/HSPA and LTE/ Accounting

functions for inter-operator charging and billing settlements.

P-GW Interconnection point to external IP networks. IP address allocation/charging/packet

filtering/policy-based control of user-specific IP flows

PCRF Policy and Charging Rules Function Flow based charging, including e.g., online credit control andpolicy control including service authorization and QoS management.

OCS/OFCS Online Charging System / Offline Charging System



RJIL Network Architecture(LTE)

SAE-GW = S-GW + P-GW


14/11314Samsung Confidential and Proprietary Information. All Contents Copyright ⓒ 2011 Samsung Electronics Co., Ltd.2014 © Samsung Electronics 14

Regional Sites (8 Super Core) Setup


15/11315Samsung Confidential and Proprietary Information. All Contents Copyright ⓒ 2011 Samsung Electronics Co., Ltd.2014 © Samsung Electronics 15

Child Circle Parenting with Regional Sites

Haryana Circle EPC Nodes connecting to Delhi Super Core Nodes and its Geo Mate Kolkata

Super Core Nodes.

Similarly, Assam Circle EPC Nodes connecting to Kolkata Super Core Nodes and its Geo Mate

Delhi Super Core Nodes.

Child Circle

Local Circle



HSS

S-GW P-GW

PCRF

IP

NetworkLTE Network

MMEeNB

eNB

ePDG

WiFi AP

ENUM

MNP

MGWSGW

SBCIP-SM-

GW

MRF

IMS Network

IMS (Minimum Set for VoLTE)

PSTNPLMN

VCC

MGCF

CSCF

TAS

SBC : Session Border Controller

CSCF : Call Session Control Function

VCC : Voice Call Continuity

TAS : Telephony Application Server

IP-SM-GW : IP-Short Message-GatewayMGCF : Media Gateway Control Function

MGW : Media GateWay

SGW : Signaling GateWay

MRF : Media Resource Function

HSS : Home Subscriber Server

MNP : Mobile Number Portability

HSS

EPC

IMS

Basic VoLTE Network Architecture

EPC Network



RJIL Network Architecture(IMS)



PDN Connectivity & Attach

APN(Access Point Name): a character string that contains a reference to the PDN where the desiredservices are available. The corresponding PGW is selected by the network based on the given APN.

PDN connectivity a type of IP connection including QoS, charging, mobility, security, policy control

aspects, as such it is differentiated from the mere IP connection.


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19Samsung Confidential and Proprietary Information. All Contents Copyright ⓒ 2011 Samsung Electronics Co., Ltd.

QCI table

Default

bearer

Persistent

Dedicated

bearer

Dedicate

d

bearer


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NW Architecture - Voice/Video Call over LTE

Use the same architecture/procedure/protocol with VoLTE

– SIP for Signaling using default bearer with QCI-5

Difference with VoLTE

– Usage of two dedicated bearers

– One for voice (QCI-1) and the other for video (QCI-2)

– Codec used for video : H.264 (H.263 also used in normal commercial network)

LTE/EPCNetwork

MME

eNB

IMSNetwork

TAS

PCRF

SAEGW BGW

CSCF

QoS control

(Voice/Video serviceinfo)

SIP Signaling

RTPVoice/Video

Voice (QCI 1)UE

Video (QCI 2)

Dedicated bearerfor media

Bearer

Traffic



Network Identities



GUTI – Globally Unique Temporary UE Identity - is assigned only by the MME during

initial attach of a UE to the E-UTRAN – masks the true identity of the subscriber

GUTI provides an unambiguous identification of the UE that does not revel the UE’s

permanent identity. It also allows identification of the MME and Network to which

UE attaches

GUTI has to main components - GUMMEI Globally Unique Mobility management

Entity Identifier and the M –TMSI that uniquely identifies the UE within the MME

For paging, the mobile is paged with the S-TMSI which is a shorter version of GUTI

On the S1 Interface, the IMSI is typically not seen just like the GUTI. Exceptions areinitial attach when no old GUTI is stored on the USIM card or in paging procedure

Identities Used in LTE - GUTI


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RNTI – Radio Network Temporary Identifier

RNTI is signaled in the MAC Layer. When MAC uses the PDCCH to indicate radio

resource allocation, the RNTI is mapped on the PDCCH depends on the logical channel

type -

C- RNTI : Temporary Cell Radio Network Temporary Identifier for Dedicated Control Channel

(DCCH and DTCH). It defines which data sent in DL belongs to a particular subscriber – all RRC

messages are marked with same C RNTI for a subscriber

P- RNTI : Paging Radio Network Temporary Identifier for Paging Control Channel (PCCH) is

derived from IMSI. It does not refer to a particular UE but to a group of UEs.

RA- RNTI : Random Access Radio Network Temporary Identifier for Random Access Response

(RAR) on DL-SCH – assigned to particular UE and is contained in the response from eNode B

for PRACH. The UE then uses this RA- RNTI to send RRC Connection Request

Temporary C-RNTI for Common Control Channel (CCCH) during random access procedure

SI- RNTI : System Information Radio Network Temporary Identifier for Broadcast Control

Channel (BCCH) – sent on PDCCH - it signals to all UEs where SIBs are found on PDSCH

Identities Used in LTE - RNTI

RNTI Values


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LTE Identities


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Bearers


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UE Temporary ID’s at different interfaces


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S1AP Interface

In between eNB and MME, the User can be identified using the S1AP ID’s.

eNB-UE-S1AP ID is the S1AP ID terminating at the eNB side

MME-UE-S1AP ID is the S1AP ID terminating at the MME Side.


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i i


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Diameter Session ID

Gx Diameter Session Id can be used to identify the diameter packets related to a

particular subscriber session.

Gx diameter session Id will be created when the session is created for the subscriber

and will stay till the session is available.


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Scenarios

P k t D t Fl i LTE


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Packet Data Flow in LTE

IMS (S h ti A hit t )


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IMS (Schematic Architecture)

3G UMTS I t ki


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3G UMTS Interworking

1. LTE natively supports VoIP only using IMS services

2. LTE also supports CSFB Circuit Switched Fallback mechanism which allows CS voice calls

to be handled via legacy RAT (Radio Access Technology) for UEs that are camped on LTE3. This is supported by SGs interface between MME and MSC. This allows the UE to attach

to the MSC and register for CS services while still in LTE. It also carries paging messages

from the MSC so that UE can be paged over LTE

4. The Network may choose a handover, cell change order or redirection procedure to

move UE to the legacy RAT

5. The UE moves to CS services on initiating a CS voice call

S3 : MME to SGSNS4: SGW to SGSN

CSFB d SRVCC


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CSFB is a solution for networks that do not have support for IMS VoIP.

The Voice Calls are handled by the CS domain and the UE is handed over at the time of a

voice call. The MME maps the Tracking Area to the Location Area.

Challenge is Call Set Up delay

SRVCC is a solution for converting and handing over an IMS VoIP call to a CS voice call

without interrupting the call when coverage of LTE is not there with handover interruption

time of less than 300 ms

SRVCC is a one way handover from LTE to UTRAN/GERAN and the UE may return to LTE

when reaching idle state The solution relies on running only one radio at a time i.e. the UE may not communicate

with both the Networks.

In this solution the MME is connected to the MSC via a Sv interface which is used for

control signaling in the SRVCC handover

SVLTE Simultaneous Voice and LTE – handset works simultaneously in LTE and circuit

switched mode – LTE provides data services and circuit switched mode providing voice

services – the mobile phone has high power consumption as two radios run together

One additional approach not initiated by operators is usage of OTT services Over the Top

Content Services like Skype / Google Talk

CSFB and SRVCC

Additional Interfaces required forinterworking with Legacy CS Networks

OTT d V LTE


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Over the Top (OTT) communication solutions such as Skype

cannot provide fully satisfactory user experience as there are no QoS measures in place

There is no handover mechanism to circuit switched network

No wide spread interoperability of services between different OTT services and devices

No guaranteed emergency support or security measures

Cannot provide services like HD Voice

VoLTE has the following advantages -

Operators can make use of wider capabilities of IP based networks to deliver high capacity

and inter operable communication services Can provide HD Voice, Video calling, HD conferencing, IP messaging and contact

management

Can provide guaranteed end to end QoS, support for emergency services and regulatory

services, global interoperability and mobility, interconnect and international roaming

Can have fallback options to circuit switched networks

OTT and VoLTE

Message Flow for CSFB Call


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Message Flow for CSFB Call

Figure shows message flow for a CSFB call from LTE to UMTS including paging from the

MSC via the SGs interface and MME for UE terminated calls and the sending of an

Extended Service Request NAS message from the UE to the MME to trigger either a

handover or redirection to the target RAT for UE originated call.

CSFB


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CSFB

SRVCC


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SRVCC

E UTRAN Connections


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E UTRAN Connections

Figure also shows the reference points for inter RAT handover between E-UTRAN,

UTRAN and GERAN

Connections after handover to

UTRAN/GERAN

Connections via E-UTRAN

SRVCC Single Radio Voice Call Continuity


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SRVCC Single Radio Voice Call Continuity If ubiquitous coverage of LTE is not available, it is possible that a UE involved in VoIP call

over LTE might then move out of LTE coverage to enter legacy RAT which offers CS voice

services

The SRVCC is designed for handover of a PS Packet Switched VoIP Call over LTE to a CSvoice call involving the transfer of a PS bearer into a CS bearer

The eNode B detects UE is moving out of LTE coverage and triggers a handover

SRVCC is used for handover from PS VoIP Call to CS Voice Call

E UTRAN with roaming


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E-UTRAN with roaming

VoLGA


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VoLGA

VoLGA – Voice over LTE via Generic Access Standards

Most Operators preferred VOLTE

The lack of software support in initial LTE devices as well as core network devices led to a

number of carriers promoting VoLGA as an interim solution

The idea was to use same principles as GAN Generic Access Network also known as UMA

or unlicensed mobile access which defines the protocols through which a mobile handset

can perform voice calls over a customers private internet connection usually over

wireless LAN

VoLGA however never gained much support because VoLTE promises much more flexible

services

WiFi Calling


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WiFi Calling

WiFi Calling needs to be enabled both in the device and in the network

New integrated functionality in the EPC with the ePDG Evolved Packet Data Gatewayin needed to allow untrusted non-3GPP accesses to interwork with the EPC and

connect to the IMS Network

The ePDG provides security mechanism such as IPsec tunneling of connections

Video Calls over LTE


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Video Calling

Video Calls over LTE

SMS Over LTE


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There are two options to deliver SMS services over LTE via the existing Short Message

Service Center SMS-C

SMS over SGs – the device sends and retrieves circuit switched based SMS messages - uses

SGs interface between MSC and MME. The device will not fall back to GSM/WCDMA whilesending or receiving messages. For SMs over SGs the existing roaming/interconnect

agreements may be reused.

SMS over IP - the device sends and retrieves SIP packet switched SMS messages - the

solution requires an SMS client that uses IMS and SIP stack , an IP Short Message Gateway

(IP SM-GW)

SMS Over LTE

SMS over SGs

SMS over IP

SMS is encapsulated & routed via IMS

IPsec


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The IP version can be IPv4 or IPv6

In case of VPN traffic IPsec will be used

The applications on top of IP in the user plane stack are all protocols of the TCP/IP

suite such as File Transfer Protocol FTP, HTTP (web browsing), POP3/SMTP (for e-mail)

and Real Time Transport Protocol RTP and SIP for real time services like VoIP

While IPsec is used decoding of TCP/UDP frames is not possible due to ciphering used

by IPsec

IPsec

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VoLTE Basics

IMS Connectivity


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IMS Connectivity

On Net Call


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On Net Call

PCFX

SCFX

Off Net Voice Call


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Off Net Voice Call

Emergency Call Flow


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Emergency Call Flow

On Net SMS


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On Net SMS


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VoLTE Requirements


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VoLTE Requirements

VoLTE Ecosystem Requirements


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VoLTE Ecosystem Requirements

VoLTE Ecosystem Requirements (Contd)


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VoLTE Ecosystem Requirements (Contd)

VoLTE Requirements


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VoLTE Requirements

User Identities in IMS Network


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Use de es S e o

Bearer Mapping


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pp g


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SIP Cause Codes


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SIP Cause Codes (Contd)


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( )


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Attach Procedure


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T300starts

T300

stops

Attach Procedure


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RACH


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RACH Trigger (Two Examples)


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RRC Connection Setup (Down Link)


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RRC Connection Setup Complete (Uplink)


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Attach Request



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Attach Request



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Attach Request



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Attach Request



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Attach Request


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Codec

Selection

Dedicated

Bearer


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QoS Negotiation


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VoLTE Call Flow

RJIL Initial Attach Request (APN=jionet)


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SAE GWUE eNB MME

S-GW P-GWHSS PCRF SPR

Power on

RRC Connection Setup

1. Attach Request(PDN Connectivity Request)

3. UE IP allocation

LTE Authentication

NAS Security Setup

2. Create Session Request

IMSI, MSISDN, APN=jionet, PCO, Bearer Context (Bearer ID, Bearer QoS – QCI:9, GBR: 0, MBR: 0)

4. CCR(Indication of IP-CAN Session establishment)

Initial Request, Subscription-Id(e.g., IMSI), UE-IP, APN, Event-Report, QoS Info(APN-AMBR(UL/DL)), EPS Bearer QoS(QCI, ARP)

5. Profile Request

6. Profile ResponseUser Profile = internet

7. Policy Decision

8. CCA(Acknowledge of IP-CAN Session Establishment)

PCC Rule for Default bearer(QCI=9, ARP=1, APN-

AMBR(UL/DL)=50Mbps/100Mbps, Offline, TFT(UL/DL))

IMSI, Initial Request, APN=jionet

11. Attach Accept(Activate Default EPS bearer Context Request)

APN=jionet, UE-IP, Default Bearer QoS(QCI=9, ARP=1, UE-AMBR(ULAPN-

AMBR(UL)=50Mbps, TFT(UL)=(UE IP, *, SIP, *, UDP), PCO, GUTI, TAI-list

12. Policy Enforcement

13. Attach Complete(Activate Default Bearer Context Accept)

14. Modify Bearer Request

15. Modify Bearer Response

Default Bearer(QCI=9)

Bearer ID

Location Update

9. Policy Enforcement

10. Create Session Response

UE-IP, Default bearer QoS(QCI=9, ARP=1, APN-AMBR(UL)=50Mbps, TFT(UL)=(UE IP, *, SIP, *, UDP)

OCS

9.1 CCR (Indication of Session, APN=JioNet)

9.2 CCA (Ack of session, APN=JioNet)

RJIL PDN Connectivity Request (APN=ims)


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OCS

4.1 CCR & CCA to/from PCRF, APN=ims)

PCRF

4.2 CCR & CCA to/from OCS, APN=ims)

PCO : Protocol

Configuration Option is

used to allocate the PCSCF

domain name /IP address

DNS : Domain Name

Server translates

hostname into IP address

PCO option is usedby UE during PDP

context activation

to request for

P_CSCF address,

DNS server details

etc

RJIL Device view after IMS registration(S-4 mini)


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The Jio Join client resides on a 2G/3G/4G LTE Only handsets

VoLTE - UE Attachment and IMS Registration message


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Part of 2

CCR Credit Control Request

CCA Credit Control Answer

RACH, Attach, Authentication and Default Bearer

Creation QCI 9 and Dedicated Bearer QCI 5 using JionetAPN and IMS APN – both bearers shown (detailed

messages already discussed)


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RJIL VoLTE Call Flow (UE to UE SIP Msgs)


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UE UE

INVITE (SDP offer)

100 Trying

180 RingingUser

alerting

200 Ok_INVITE

Ack

BYE

200 Ok_INVITE

Hook off

183 Session Progress (SDP answer)

PRACK

200 Ok_PRACK

UPDATE (SDP offer)

200 Ok_UPDATE (SDP answer)

RTP/RTCP

IMS

INVITE (SDP offer)100 Trying

183 Session Progress (SDP answer)

PRACK

200 Ok_PRACK

180 Ringing

183 Session Progress

UPDATE (SDP offer)

200 Ok_UPDATE (SDP answer)

200 Ok_INVITE

Ack

BYE

200 Ok_INVITE

Used only when

network based

ringback is used

Case Study : M to M VoLTE call(1)


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Both Devices are in Idle Mode



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IMS to PSTN/PLMN call flow


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VoLTE - UE to UE Call establishment (Originating Side)


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RAR : Reauthorization Request, AAR : Authentication Authorization Request, SDP : Session Description

Protocol

VoLTE - UE to UE Call establishment (Terminating Side)


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VoLTE - UE to UE Call clearing (Initiated message)


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VoLTE - UE to UE Call clearing (Received message )


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VoLTE - VoLTE UE to CS call establishment (Originating Side )


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VoLTE - VoLTE UE to CS call establishment (Originating Side )


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VoLTE - VoLTE UE to CS call Clearing (Initiated )


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VoLTE - VoLTE UE to CS call Clearing (Received )


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MOCN Trial set up

12th Jan 2016

MOCN Trial set up – Schematic


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S6a/ S13MME

SGi

Internet

Shared eNB

HP

Switch( 1+1 )

SGs

OAM

S6a/ S13

OAM

SGsMSC / IWF

HSS / EIR

SAEGW

S1 - MME

S1 - U

SGi

OCS / OFCS

Gx

Gy/Ga

PCRFGx

OAM

S11

DCN NW

OAM

OSS

Gy/Ga

Juniper

M120

CAG

( 1+1 )

Interfaces ready for Data call

SGi

S6a/ S13

SGs

Gx

Gy/Gz

ALU

7750SR

CCR( 1+1 )

Interfaces WIP for voice call

Internet data call successfully tested

Voice call testing readiness is in progress

Not mandatory for first call


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