LTE Voice Services Agenda

• Voice Options in LTE

• Comparison of Voice Options

• Voice Deployment Strategies

• MultiService Forum

• VoLTE Recent Announcements

• Voice Enhancements – Rel 8 & 9

• Conclusion Voice Options with LTE

• Data Only

• Circuit Switched Fallback (CSFB) to 2G/3G CS

• VoLGA

• VoLTE (IMS-based) – On LTE Only – On LTE & 2G/3G via SR-VCC – On LTE & 3G via UMTS PS

• Over-the-top (OTT) – à la Skype Data Only

• PROS – Simple – Device availability – Easy and gradual deployment of LTE • CONS – Not useful for smartphones – Single radio limitation – May encourage OTT competition

The initial LTE offering for many carriers is based on devices with no native voice support - eg PC Dongles CS Fallback Procedures - 1

• Registration:

– a combined UE registration procedure on both LTE and GSM/UMTS – from the MME to the MSC via the SG interface – GSM/UMTS Location Area ID (LAI) calculated from the LTE Tracking Area ID (TAI)

• Call Origination

– UE requests the MME to perform a CSFB – MME requests the eNodeB to redirect UE to the target 2G/3G cell (determined via UE measurements or preconfigured) – The eNodeB redirects the UE to the target cell – The UE performs an RRC on the target cell (and possibly a location update as well) CS Fallback Procedures - 2

• Call Termination: – The MSC sends the page request to the MME over the SG interface – The MME pages the UE with the CSFB indicator – UE responds with a service request with the CSFB indicator – MME instructs the eNodeB to redirect UE to the target 2G/3G cell (determined via UE measurements or preconfigured) – The eNodeB redirects the UE to the target cell – The UE performs an RRC on the target cell (and possibly a location update as well) • Active Data Sessions: – Must be handed-over to the 2G/3G or dropped – Via a Packet Switch HandOver (PSHO) on 3G – Requires Dual Transfer Mode (on both 2G and UE) if fallback on 2G CS Fallback Procedures - 3

• SMS: – No fallback for SMS origination/termination – UE sends/receives SMSs to/from the MME – MME sends/receives SMSs to/from the MSC over the SG interface CS Fallback Architecture

GERAN

MSC/VLR

UTRAN

Um SGs HSS S6a Ch, Sx Uu

S1-MME MME PCRF

S10 S7 RX+ S11

UE eNodeB S-GW P-GW IMS LTE Uu S1-U S5 SGi

X2 CS Fallback Call Flow

UE

UE eNodeB BSS MME MSC SGSN S-S-GW P-GW 1a. Extended Service Request UE to MME: I want to move to UTRAN 1b. S1-AP Request message with CS Fallback indicator 1c. S1-AP Response message MME to ENB: UE wants to move to UTRAN

2. Optional Measurement Report Solicitation ENB to UE: where are you? 3a. PS HO as specified in 23.401 [2] (preparation phase and start of execution phase) if PS HO fails -» CSFB fails 3b. Suspend ONLY FOR GERAN SGSN deactivates GBR Bearers (SGW+PDN) 3c. Update Bearer(s) 4a. Location Area Update or Combined RA/LA Update LA in UE is nok? Then LAU 4b. CM Service Request 4b. A/Iu-cs message (with CM Service Request) UE to MSC: Context Modification

5. CM Service Reject 5. CM Service Reject If the MSC is changed Location Area Update or Combined RA/LA Update

6. CS call establishment procedure The call is established on 3G 7. PS HO as specified in 23.401 [2] (continuation of execution phase) Once the call is ended, PS HO to LTE CS Fallback – UE and Network Requirements • UE: – Support for both LTE and GSM/UMTS – Support for combined EPS/IMSI attach, detach, and location update procedures – Support for CS fallback and SMS procedures • Network – 2G/3G MSCs: – Support of SGs interface to the MME – Support of simultaneous paging on the A, Iu, and SGs interfaces – Support of sending and receiving SMS over the SGs interface • Network – LTE MME: – SGs interface support – MSC procedures such as IMSI attach/detach, location update, and paging – CS fallback SMS procedures • Network – LTE E-UTRAN: – Redirect UE to a GSM/UMTS cell – Forwar • Network Engineering – Additional LTE traffic over the GSM/UMTS network (RAN and MSC) – iTrack ng/location and coverage areas shall be consistent between LTE and GSM/UMTS CSFB issue due to TA/LA misalignment

Source : GSMA IR.88 LTE Roaming Guidelines

In the case of TA/LA misalignment, the Roaming Retry procedure allows transferring the incoming call from MSC1 to MSC2, which increases both the call setup time and the call success ratio. CS Fallback – PROs & CONs

• PROS – Reuse of all GSM/UMTS voice infrastructure including existing OSS/BSS systems – lFastout rol of voice services – Voice service transparency between LTE and 2G/3G – Minor upgrades on legacy network (SG interface similar to the MSC- SGSN G interface) • CSON – Call set-up delay i.e. 500+ msec – Concurrent data session may be dropped VoLGA

• Based on 3GPP TS 23.879 option 2, with further development by the VoLGA Forum • Us es a new dedicated Interworking Function (IWF), also known as VoLGA Access Network Controller (VANC), to interwork the LTE and GSM/UMTS networks. Inserted between the EPS and MSC • All voice traffic goes through the LTE but using the 2G/3G voice Source: 3GPP VoLGA Stage 2 V2.0.0 (2010-06-14) infrastructure in a transparent manner VoLGA

• PROS – Reu se of all GSM/UMTS voice infrastructure including existing OSS/BSS systems – Fast rollout of voice services – Voicer se vice transparency between LTE and 2G/3G – No changes on legacy network – Fast LTE-to-GSM/UMTS handovers – Supports concurrent voice and data sessions • CSON – Voice traffic hits both the LTE and the 2G/3G networks – tIn roduces three new network elements: VANC, security GW, AAA server – Does not support advanced IMS services – dNot accepte by 3GPP IMS – Historical Overview

• Ra tionale & Purpose – IMS is an SIP-based (Session Initiation Protocol) session and service control platform that enables delivery of multimedia applications across a broadband wireline or wireless network – IMS was first introduced in the 3GPP Release 5 standards and predates the development of LTE by nearly seven years – B uilds on IETF SIP technology (perceived Internet scaling and low cost) – Split the access network from the service network permitting common service network across fixed, mobile and internet – Multimedia in addition to voice; No need to standardised services only enablers • The Reality – IMS was intended to be access agnostic, but interaction with existing technologies requires access specific functionality be added to the IMS network. – Complex standard with many options to SIP – Large legacy service load; Service parity with CS is complicated – lComme rcia systems available, but take up has been very slow – 3GPP extensions in 3GPP TS 24.229 for management, security and billing reasons • Initial Deployment Issues – Cost – IMS requires a complete new core network – Risk – Scaling up to support 10’s of millions to subscribers is still an unknown. – Performance is also seen as a risk – Integration – Existing services have to be integrated with IMS based service – Operator business models – Services run as separate P&L centres IMS – Key Components

The Call Session Control Functions (CSCF) are the core components of the IMS. There are three CSCF: • Proxy-CSCF (P-CSCF): The P-CSCF is the first point of contact for a user. The PCSCF behaves like a proxy, i.e. it accepts requests and forwards them on. • Interrogating-CSCF (I-CSCF): The I-CSCF is the entry contact within an operator’s network for all connections destined to a subscriber. • Serving-CSCF (S-CSCF): The S-CSCF is responsible for handling the registration process, making routing decisions, maintaining sessions, and downloading user information and service profiles from the HSS. VoLTE with LTE Access Only

• Based on 3GPP TS 23.228 IMS supporting both legacy voice services and advanced multi- media services • GSMA IR.92 defines the profile HSS for Voice and SMS based on One MME PCRF Voice Initiative IMS

eNode • Can be extended to support voice UE S-GW P-GW P-CSCF AF B

service service continuity to 2G I-CSCF S-CSCF GSM network (i.e. handovers) • Can be extended to support voice service service continuity to 3G UMTS/HSPA network (i.e. VoLTE with SRVCC-based voice delivery

• SIP signaling between the UE and the IMS core • Over the existing transport capabilities of the GSM/UMTS network • Usf e o ICS (CS-to-IMS call control) and SRVCC (handovers) • Support simultaneous PS and CS services, the IP connection is provided by the legacy packet core as per the Gm reference point. 3GPP TS 23.216 V9.6.0 (2010-12): "Single radio voice call continuity (SRVCC); Stage 2 (Release 9)". VoLTE with UMTS-PS voice

delivery Um/Uu Iu-CS/A UTRAN UE GERAN MSC

I2 • UM TS PS access, allowing voice, Iu-PS/Gb data and multimedia services to SV be carried simultaneously over SGSN

the same PS-domain IP S3 3GPP connection (no need for ICS and IMS SRVCC) S6a MME HSS

• Concurrent voice and data S1-MME SGis multimedia services S11

• Seamless mobility between the Uu S1-U UE E- P-GW LTE and UMTS networks with the UTRAN use of PS handovers and handbacks VoLTE Procedures - 1

• Registration: – The UE always registers on the IMS network (for both LTE and GSM/UMTS) – Registration includes the ICS and SRCVCC indicators (if supported) • Call Origination – Session is set-up as standard IMS procedures according to 3GPP TS 23.228 – eIn th GSM/UMTS, the ICS-enabled UE sets-up 2 signaling paths (one over legacy packet to the IMS SCC AS, one CS-bearer via legacy procedures to the MSC) – CCThe AS S combines the 2 procedures on the CS-access leg and establishes the IMS-leg of the call VoLTE Procedures - 2

• Call Termination: – IMS terminating session is initiated toward the UE’s selected contact address – Upon receiving the invite message, the ICS-enabled UE originates a CS call to the SCC AS using its associated directory number – Sim ilar procedure as for call origination • LTE to UMTS PS Handover: – Ind itiate by the eNode B via a request to the MME to establish resources in the target RNC, SGSN and SGW – The MME only needs to coordinate and perform a PS handover. Because both the voice and non-voice sessions are over PS, there is no separate CS session to hand over • Direct tunnel from the SGW to the RNC via an S12 interface • Indirect tunnel from the SGW to the SGSN to the RNC VoLTE Procedures - 3

• SRVCC-based handovers: SRVCC enables calls to be seamlessly handed over from the LTE to the GSM/UMTS access network, while session/call control remains in IMS. – dInitiate by the E-UTRAN to the MME based on the measurement reports it receives from SRVCC-enabled Ues – The MME then separates out the voice bearer from the non-voice bearers and starts the handover procedure with both the MSC and SGSN – MSC instructs the target Radio Network Subsystem (RNS) to prepare for the handover by allocating the necessary resources to set-up the CS access leg – theC MS initiates the IMS session transfer to the CS domain (3GPP TS 23.292 and TS 23.237) – When complete, the CSCF switches the VoIP call to the CS access leg that has been established for the handover. – It notifies the MME that it is ready for handover – Then MME i structs the E-UTRAN to handover VoLTE Procedures - 4

• SMS. – requires the use of the IP Short Message Gateway (IP-SM-GW), as defined by 3GPP TS 23.204 Release 7. This gateway is required for SMS message delivery between the SMS Center and any IP-based UE – IP-SM-GW receives a message from the SMS Center, it forwards it to the CSCF, which in turn delivers it to the UE – the IP-SM-GW may deliver SMS messages using the IMS, PS or CS domains – the UE receives its SMS on the IMS, UMTS or GSM network – The IP-SM-GW attempts SMS delivery in the order set by the operator policy and/or user preferences. For example, the IP-SM-GW may first attempt SMS delivery on the LTE/IMS network, followed by the packet core, and finally by the circuit core. VoLTE – UE and Network Requirements

• VoL TE with LTE access only – IMS core — CSCF, Telephony Ap•plication Server (TAS), and other components – UE supporting VoLTE client – SIM cards (UICC) supporting the ISIM application – an IP-SM-GW is required for the support of SMS. • VoLTE with LTE and UMTS PS access – upgrades to the UTRANs in the GSM/UMTS network – Optional upgrade to the SGSNs for the indirect tunneling – ThTRANe U not only requires an upgrade to 3GPP Release 8, but must also support Robust Header Compression (ROHC) and a radio allocation process that offers semi-persistent scheduling. – TRANThe U must also support the S12 interface between the RNC and SGW used for the direct tunneling method. – ThSNe SG must also be upgraded to 3GPP Release 8 to support the S4 interface to the SGW. This interface is used for the indirect tunneling method. • VoLTE with ICS and SRVCC – UE support of the ICS and SRVCC clients. – On the IMS network, two IMS application servers: SCC AS and SRVCC AS. – ForSM VoLTE G support, the SCC AS along with the MSC and Home Location Register (HLR) must support USSD. – SRVCC also requires upgrades to the E-UTRAN, MME and HSS in the LTE network. – To support SRVCC handovers, the MSC must be upgraded with the Sv interface and must support coordination of the SRVCC relocation and session transfer procedures. Upon successful relocation, the MSC must also be able to automatically register the UE with the HLR. – The HLR may also need upgrading to support the new IP-SM-GW in the network. VoLTE – PROs & CONs

• PROS – IMS enables new revenue generating, advanced voice and data blended services (e.g. GSMA Rich Communication Suite (RCS)) – Efficient concurrent voice and data handovers UMTS PS access – SWith IC and SRVCC, voice service transparency between LTE and 2G/3G – rPrese ves LTE’s bandwidth during voice calls while minimizing call setup delay – Assus re global interoperability and roaming – sProvide the largest possible ecosystem which affects such matters as handset supply and multivendor interworking – sProvide an all-IP network for operational savings and HD voice • CONS – Sizable investment in the LTE on IMS core — CSCF, TAS, IP-SM-GW – WiS th IC and SRVCC, the SCC and SRVCC ASs are required as well as SRVCC upgrades to the E-UTRAN and MME, the deployment of an MGCF and upgrades to all border MSCs for support of the Sv interface. – P ossible break in the voice stream when a session/call is handed down to the GSM/UMTS network Over-The-Top (OTT)

• Fills the gaps in carrier voice strategy • OTT technically viable on LTE and UMTS • Apps-stores make it easy for users to install clients • PROS – Noit t lim ed by legacy continuity – Prervees L TE data rates during voice calls – No “IMS complexity tax” – Int egration with presence and productivity apps – Non-traditional voice apps (Voice Twitter?) – Support of wideband voice – Competitive pricing • CONS – B usiness case unproven – QoS management unclear – D PI blocking possible – R oaming challenges with data roaming charges & QoS control – Global interoperability with the PSTN – Availability outside LTE footprint unclear – R egulation Network Impact - Comparison Requirement CS Fallback VoLGA VoLTE LTE Only VoLTE UMTS PS VoLTE ICS and SRVCC

New network None • VANC • IMS core • IMS core • IMS core equipment • Security gateway • IP-SM-GW • IP-SM-GW • IP-SM-GW • AAA server • SCC and SRVCC AS • MGCF Legacy network All MSCs overlaying LTE None None •UTRAN • Only MSCs at LTE edge upgrades coverage •SGSN for indirect • HLR tunneling method EPS and/or IMS • E-UTRAN • E-UTRAN • HSS • HSS • E-UTRAN upgrades • MME • MME • MME • HSS 3GPP compliance for Yes No Yes Yes Yes IOT ease •Standards advanced by VoLGA Forum Terminal changes Likely small Likely substantial Likely small Likely small Likely substantial • CS-fk s allbac upport • VoLGA support • IMS client • IMS client • IMS client • SRVCC support • ICS support • SRVCC support LTE and GSM/UMTS • Requires LTE and None None None None coverage engineering GSM/UMTS coverage considerations overlap •fSimilar con iguration for tracking and location areas Performance - Comparison

Requirement CS Fallback VoLGA VoLTE

LTE Only VoLTE UMTS PS VoLTE ICS and SRVCC

Network providing voice GSM/UMTS GSM/UMTS IMS IMS IMS services

Network providing voice GSM/UMTS LTE LTE UMTS GSM/UMTS radio coverage

Network providing SMS GSM/UMTS, but user GSM/UMTS, but user LTE/IMS network LTE/IMS network LTE/IMS network remains on the LTE remains on the LTE network network Quality of voice call set- Some delay Excellent Excellent Excellent Excellent up

Quality of LTE-to- N/A Excellent – CS based N/A Excellent, PS-based Possible break in voice GSM/UMTS voice stream with SRVCC handovers handover Support for in-call No No No Yes Yes: 3GPP Release 10 handbacks

Support for concurrent • No for GSM Yes Yes Yes Yes voice and data • Yes for UMTS

Support for advanced No No Yes Yes Yes services

Operational benefit of No: LTE access and IMS Partial: uses LTE access, Yes Partial: uses IMS, but Partial: uses IMS, but flat all-IP network not used but not IMS UMTS PS access GSM/UMTS access VoLTE and Roaming

UE Options (by Visited LTE Network Options (by priority) priority)

CSFB VoLTE VoLTE+CSFB

CSFB CSFB – CSFB

VoLTE – VoLTE VoLTE

VoLTE+ CSFB CSFB VoLTE VoLTE Recommendations

Requirement CS Fallback VoLTE

LTE Only VoLTE UMTS PS VoLTE ICS and SRVCC

Operator with LTE network with complete √ national coverage GSM operator starting to deploy LTE √ √ √

UMTS operator starting to deploy LTE √ √ √

Operator planning to deploy UMTS VoLTE √ √

Operator with GSM/UMTS and CDMA networks √ √ √

Operator with wireline and wireless networks √ √ √

Operator offering or planning to offer √ √ √ advanced IMS services LTE Voice Deployment Strategies

LTE Step 1: Spotty LTE Coverage: 2G/3G CSFB across the 2G/3G coverage area

LTE Step 2a: VoLTE Launch: LTE Step 2b: VoLTE Launch: 3G UMTS PS across 2G/3G 3G SR-VCC across 2G 2G coverage area 2G coverage area

LTE Step 3: Full VoLTE Coverage 3G Target Solution New terminals use LTE only 2G Legacy terminals on legacy networks MultiService Forum (MSF) VoLTE Interoperability Event 2011

Event backed by the GSMA to validate a number of GSMA technical recommendations, namely: • PRD IR.65 - IMS Roaming and Interworking Guidelines, • PRD IR.88 - LTE Roaming Guidelines, • PRD IR.92 - IMS Profile for Voice and SMS.

http://www.msforum.org/ VoLTE – Early Adopters (Aug 2012)

• US carrier MetroPCS claims to have beaten SK Telecom to the title of “world’s first VoLTE (Voice-over-LTE) operator”, as commercial deployment in this space starts to ramp up. • South Korea’s SK yesterday issued a statement saying that the launch today of its HD Voice service will see it become the first operator in the world to commercially switch on VoLTE services. However, MetroPCS has stolen SK’s thunder slightly by saying that it switched on its own service yesterday, ahead of SK. The US operator is now selling the VoLTE-capable LG Connect 4G Android smartphone at “select US stories” and says it will “continue to roll out VoLTE services and phones in the coming weeks.” SK’s launch today is supported by the Samsung S3 smartphone. • Meanwhile South Korean number three operator LG Uplus is also switching on its VoLTE service today in Seoul, supported by LG’s Optimus LTE2 smartphone. The country’s second- largest operator, KT, has said it plans to launch VoLTE in October. • Sepa ar te reports this week claim US operator T-Mobile USA is now considering supporting VoLTE services sometime in the future, a move that will follow similar launches by AT&T and Verizon Wireless. VoLTE – Joyn Brand

• T-Mobile, Vodafone launch Joyn-branded RCS services in Germany – Aug 2012-March 2013 • Free app on iOS and Android • Based on GSMA Rich Communication Suite (RCS) • Already available in Spain – Telefonica & Vodafone • Available in fixed network later • 1 M Joyn Subs - SK Telecom Feb 2013 • 30e op rators in 18 countries are committed to Joyn – GSMA Jan 3013 Joyn Service Launches

Country Operator Launch Date Device support

Germany T-Mobile Mar 2012 Android 2.3+ and iOS apps

S Korea SK Telecom Dec 2012 Android 2.3 app iOS app slated early 2013 app S Korea KT Freetel Dec 2012 Android 2.3 app iOS app slated early 2013 S Korea LG U+ Dec 2012 Android 2.3 iOS slated early 2013 Spain Orange Nov 2012 Android v2.2+ and iOS, Samsung Galaxy SIII, LG Optimus L9, One S HTC, Nokia Lumia 920, Sony Xperia Z Spain Movistar Nov 2012 As Above

Spain Vodafone Nov 2012 As Above

USA MetroPCS Oct 2012 Android v2.2+

Germany Vodafone Aug 2012 Android v2.2+ and iOS Voice Enhancements

• Release 8 – Semi-Persistent Scheduling (SPS) – TTI Bundling. • Release 9 – Emergency services – Location services Conclusion – Determining Factors

• Ti ming of the LTE network launch: near or far future • LTE coverage: complete or partial national coverage • Type of network currently deployed: GSM, UMTS, fixed/mobile converged, GSM/UMTS/ CDMA converged, UMA, or IMS • Planned network upgrades to UMTS, VoLTE with UMTS HSPA+, or other technologies • Ti ming for the introduction of new advanced multimedia services • Decision to implement an interim solution or go straight to the end-goal solution • Voice over LTE options/option combinations of roaming partners Relevant Standards

3GPP • 23.204: IP-SM-GW • 232 . 16: Single Radio Voice Call Continuity (SRVCC) • 232 . 21: Architectural requirements • 223. 28: IP Multimedia Subsystem (IMS) • 232 . 37: IMS Service Continuity (ISC) • 23.272: CS Fallback • 232 . 92: IMS Centralized Services (ICS) • 122. 73: IMS Supplementary Services • 423. 01: GPRS Enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Access • 823. 79: Study on Circuit (CS) Domain Services over Evolved packet Switched (PS) Access GSMA • PRD IR.65 - IMS Roaming and Interworking Guidelines, • P RD IR.88 - LTE Roaming Guidelines, • P RD IR.92 - IMS Profile for Voice and SMS • P RD IR.64 - IMS Service Centralization and Continuity Guidelines THANK YOU