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Deployment of the IMS at Telefnica Germany, fixedand mobile: why and how.

Workshop - Servios de Comunicao de Prxima Geraohttp://atnog.av.it.pt/wscpg/

Aveiro, 27 de Abril, 2012 - Instituto de Telecomunicaes

Antonio Cuevas

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Contents

ICurrent IMS deployment at Telefnica Germany (DSL, life 2011)Why?

How? And what?

Plans for IMS for mVoLTE

RCSe

Conclusions and discussion

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Current IMS deployment at Telefnica Germany

DSL, about 300 000 clients, life 2011

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IMS was almost dead

IMS is very complicated and plain IMS just offers voiceAs long as operators can keep offering voice over CS, no real need or

business case to migrate to IMS

IMS was almost dead. See next!

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History of Telefnica Germany is essential to understand theintroduction of IMS

a collection of Networks, created through various acquisitions

National mobile network(German division of the mobile

spin-off from British Telecom

National wholesale Local-loop-unbundling (LLU) fixed

broadband network (Germandivision of Spanish incumbent)

Regional fixed telephony andbroadband networks (German

division of Telecom Italia)

Telefnicapurchased O2in

2006

Telefnica Germanypurchased

HanseNet in 2010

Mobile + Broadband +Broadband + Fixed

networks

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Introduction of the IMS

O2, mobile only operator, never saw the need to introduce the IMS

Telefnica Deutchland had a National wholesale Local-loop-unbundling(LLU) fixed broadband network

No CS voice, only VoIPVoIP was subcontracted

In 2006, Telefnica S.A. bought O2

Create a German Integrated Operator

Create own fixed VoIP platform

No need to replace CS voice, there was not in fixed domain

IMS was selected (2008) for replacing the subcontracted VoIP (fixed)

Only in latter stages will the IMS replace CS voice (fixed and mobile)

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Interfaces to resellers

CRM /Prov.

1st levelCustomer

CareBilling

SystemsCPEMgmt

Subscriber A

Data Access -Internet

Voice ServiceSIP Terminal

Reseller

CustomerSelfcare

PortalHttp(s), XML Http(s), XML File transfer Http(s), XML

ResellerDiagnosis

PortalReseller

DSL LDAPAccount

Setup Portal

ResellerDSL

DiagnosisPortal

ResellerSelf CarePortal(Admin)

CustomerSelf Care

PortalResellerReport

Delivery

User Interfaces Options

Subscriber B



Subscriber C



System Provider - Telefnica

Telefnica Supporting Systems

Rese

ller

Prov

ision

ing

APIVo

ice

&DSL

Ticke

tInterface

Diagnos

isAPI

Billing

Interface

Su

bscri

ber

CDR&

Who

lesa

leBill

Rese

ller

/Su

bscr.

Fea

ture

Con

tro

lAPI

Electronic Interfaces / API Options

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VoIP-AS Platform

User Equipment (UE) Voice Class IV Infrastructure

SIP

Media

Server

Media Media SIP

Provisioning

System

Provisioning

Distributed SBC Platform

End-UserSupporting Systems

(Billing, Monitoring, Provisioning, etc.)

Media

(Mb)

API

Diameter

(Rf)

SIP (Mw)

IMS Core

Provisioning

RADIUS(Rf)

Diameter(Rf)

HTTP(S)

SIP

(ISC)

!"# % &'(

Other Resellers

HTTP(S)

API

HTTP(S)

The Big Picture

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A standard IMS!

SBC: P-CSCF (and IBCF)

IMS Core: CSCF (+HSS)

Supporting Systems: charging plus provisioning of users

Standard interfaces (note RADIUS and not DIAMETER for the SBC Rf.)

First for DSL network, not for mobile UMTS networks

No PCRF (still QoS granted, see next)

LTE+EPC mobile network in a next step

Media does reach the P-CSCF (SBC)!!!! For lawful interception

Resellers have an API to the support systems. Used, among others, to provisionusers. Support systems configure IMS core and AS

Resellers and users have a web-based self-care interface for the telephony

service provided by the AS

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VoIP to the Home: the CPE

Core is IMS-IPBut how to bring VoIP to the home? VoIPphones are very expensive

The terminal (CPE)

Router + NAT

Digitizes existing analog and ISDNphones

!No separate circuit switched networkfor the phone. QoS mechanisms sothat IP data does not hamper VoIP

DSLAM

ATM Voice PVC CBR

ATM Data PVC UBR

MAC 1

MAC 2

Beispiel: 2 parallele Gesprche

SBCSBC

IngressEgress

SBCs

Class

V

Class

IV

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A robust network

P-CSCF logically distributed: easyand efficient to achieve resiliency

SBCs geographically distributed allover Germany

But IMS core elements are not

logically distributed: redundancyneeded to achieve resiliency

Two core sites: Hannover and

Nrnberg

Main engineering tasks:

Load Distribution

Detecting when nodes fail

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Services and features

MMTEL Services.Many offered, deployed a few:

Call forwarding

Voice2mail

Call blocking / barring

Call logs

Parallel ringingFax2mail

AND:

User Web UI

FAC control

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Services and features

Multi-resellerCall capacity per subscriber (no to exceed DSL BWlimit)

announcements

Dial plan, call categoriesoperator / reseller barringsDestination number normalisation

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Plans for IMS and mVoLTE

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IP and VoIP in mobile networks are not new

Release 99, from 3GPP

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But there was a back door

Voice could still use circuit switched

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And operators were lazy and kept using circuit switched forvoice

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In LTE-EPC there is no back door

To have voice, operators must use IP => ALLis IP

LTE

Voice

Go IP!

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Voice over IP means:

Skype (not wanted, I imagine!)For operators, VoIP "IMSTelefnica Germany has already deployed

the IMS (great advantage). Voice over mobileLTE (mVoLTE) will use it

Telefnica Germany will be the first OB inTelefnica to have mVoLTE and one of the

first in the world.

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LTE and Voice: Hop, Step and Jump

20

WhitespotDSL

Replacement

(fixed VoLTE)

1 2 3

Mobile DataWith

Circuit Switched

Fallback

(CSFB)

Mobile DataWith

IMS-based

Voice

(mobile

VoLTE)

Fixed SubscriberProvisioning

Mobile SubscriberProvisioning

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mVoLTE Challenges

From day 0 we could do voice calls over LTE (tests)

IMS pre-prod and test eNode B in Mnchen

As we can also do voice calls over WiFi (tested from Boston, Sydney,

Madrid,!)!!!

No Wonder: IMS uses IP and IP is agnostic to the layer 2 access

technology. And LTE is just another radio access technology

So!thats it? Nothing to do???

NO!!!!!

Actually, mVoLTE is one of the most challenging projects. Why? See next

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Challenges and Pitfalls of mobile VoLTE

An operator extending an IMS deployed for fixed services into the mobiledomain faces some key questions.

22

Mobile IN

Services

Mobile voicecore

IMS Core

Basic VoIP

2G/3G LTE

FM

Mobilesubscriber

provisioning

Fixedsubscriber

provisioning

xDSL(VoBB)

fixedmobile converged

1

1. Subscriber data

Mobile subscribers on tofixedHSS vs. evolution of

HLR to be a mobileHSS

2 2 2. Consistent services

Customer should not noticewhen he is upgradedto

IMS-based mobile voice

3

3. Re-use vs. re-implementation

of IN-based services4

4. Availability of SRVCC in

devices

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Many possible scenarios to consider:

When will Circuit Switched Fall Back (CSFB) beavailable (devices)?

When will devices have IP-LTE voice capabilities?What to deploy in our network?

Coexistence of 3G/2.5G and LTE

And none of these scenarios is easy!!!

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The challenges

Two networks coexist. Coverage and mobility:What happens if a device is having a voice callover LTE Packet Switched (PS)-IP and moves to a

3G network where, even if PS is available for data,

circuit switched (CS) must be used for voice?

PS to CS handover! Not Simple!!!

devices will not have two radios (too much baterypower)

Is the control of the call also transfered??

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The challenges

Two networks coexist. And the difference is not justthe network technology (data transport, CS vs. IP)but also the service and user control.

What is the user database? HLR vs HSS

Users will employ both networks, do they need to bestored in both databases?

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ICS (IMS Centralised Services)

IMS registration: MSC impersonates UE when UE in CS

trigger: CS Location Update

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ICS (IMS Centralised Services)MSC translates signaling: CS SS#7 => SIP

MGW translates media

1. CS call setup (B)

2. INVITE (B, SDP from CS-MGW)



4. IN VITE (B, SDP from CS-MGW)

non ICS UE A MSC Serv er MGW SCC ASS-CSCF UE B

6. Completion of Session Setup Procedures

CS domain bearer IMS bearer

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ICS (IMS Centralised Services)MSC translates signaling: CS SS#7 => SIP

MGW translates media

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VoLTE calland SRVCC

LTE/EPC

Mobile CS

IMS

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Handover to mobile CS(SRVCC)

LTE/EPC

Mobile CS

IMS

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UE SourceE-UTRAN

SourceMME

MSC Server/MGW

TargetMSC

14. Handover Command

TargetBSS

1. Measurement reports

3. Handover Required

S-GW/ PDNGW

2. Decision for HO

5.PS to CS Req

6.Prep HO Req

7. HO Request/Ack

8.Prep HO Resp

9. Establish circuit

19. HO Complete

20.SES (HO Complete)

21. ANSWER

13.PS to CS Resp

15. HO from EUTRAN command

HSS/

HLR

23b.UpdateLoc

10. Initiation of Session Transfer (STN-SR or E-STN-SR)

11. Session transferand Update remote end

IMS

12. Release of IMS

access leg

22. PS to CS Complete/Ack

TargetSGSN

16. UE tunes to GERAN

17. HO Detection

18. Suspend (see TS 23.060)

18. Suspend18. Suspend Request / Response

22a. Bearer handling and suspension

4. Bearer Splitting

GMLC24. Subscriber Location Report

23a. TMSI Reallocation

SRVCCdetail:

EPC and

CS Mobile

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User database HSS vs. HLR

HSS was in introduced in 3G UMTS mobile networks

HSS is the evolution of the HLR, the subscriber database in GSM

mobile networks

IMS CSCFs (Call Session Control Function, enhanced SIP

proxies) are designed to Interact with HSS

So!what is the problem?

Our 2.5G, 3G and, even, LTE/EPC keep using the HLRand!

IMS is NOT designed to interact with HLR, just with HSS!!

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So, we deployed the IMS in DSL with itsown HSS

And w i th i t s own prov is ion ing

mechanismsAs a result, IMS-HSS Fixed Worldprovisioning is independent from the

mobile HLR provisioning (and billing andmany other FAB topics)

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Most evident, academical and straightforward solution would be to migrate themobile users from the HLR to the HSS

But there are about 18M mobile HLR usersand 300K HSS users!

High Risk!

Still, the target is one consolidated databasefor HLR & HSS subscriber data and for mobileand fixed subscribers.

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User database HSS vs. HLRTelefnica is planning to go for UDC

Non-UDC Network

NE

OSS, Self Care System

NE

NE

NE

NE

UDC Network

NE-FE

OSS

NE-FE

NE-FE

NE

NE

UDR

.

.

.

.

.

.

Ud

Ud

Ud

Provisioning Interface

Provisioning Interface

Network Interface Network Interface

Self Care system

Provisioning FE

Ud

UE

Ut self provisioning

UE

Ut self provisioning

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RCSe

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RCSe

Nothing new: IM.One of the first integrated IM was in Portugal

Needs to be different from existing IM: easy to use, universal, native on

devices, etc.

Uses the IMSAlthough RCS is standardised since long, it is only now, (as a reaction to

WhatsApp), that operators will use it

Presence was very complicated => RCSe

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ENUM and IMS interconnect

Currently, a global ENUM database is not yet implented ("DNS)IMS to IMS interconnection is very rare!

OK because IMS is only offering voice (mainly) and voice can be

interconnected over the PSTN

But, for IM, the PSTN can not be used: need of interconnection

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Interacction with mVoLTE

Terminals may have the RCSe APP but, still, use Circuit Switched forvoice. Problem to be solved.

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Telefnica Germany initially introduced the IMS as a replacement of a standaloneVoIP infrastructure.

The long-term strategic goal is to use the IMS as a tool to convergedifferentnetworks

consolidation of networks: a strategy for IMS introduction is related to anddependent on convergence and evolution strategies in other parts of the network.

In our experience, it is not easy to maintain a mid-term IMS evolution course whileshort-term disruptive influences cause Fear, Uncertainty and Doubtthroughoutthe organisation.

It is also not easy to maintain the interest of commercial units in the advancedfeatures promised by IMS over a many-year transition period.

Finally, a key factor for IMS is an organizational convergence, so that previously

separated teams from fixed and mobile divisions (often from completely differentcompanies) join forces to address the challenges that must be answered toenable technical convergence to take place.

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Introduction to IMS (backup slides)

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References

The 3G IP Multimedia Subsystem (IMS): Merging the Internet and the CellularWorlds

Gonzalo Camarillo et al.

John Wiley & Sons

ISBN-13: 978-0470871560

The IMS: IP Multimedia Concepts and Services

Miikka Poikselka

Wiley

ISBN-13: 978-0470019061

The IMS Service Platform: A Solution for Next Generation Network Operators to

Be More Than Bit Pipes

Antonio Cuevas, Jose I. Moreno, Pablo Vidales, Hans Einsiedler,

IEEE Communications Magazine, ISSN 0163-6804

August 2006.

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IMS as a merge of two worlds

IMS is a SIP platform running and interacting with a UMTSmobile network. Thus merge of two worlds, IETF and 3GPP

3GPP. Standardizes the UMTS mobile network:

!

IMS was introduced in UMTS release 5 (June 2002)

!Keeps evolving: Release 10

IETF. Internet standardization, among others SIP

!

More than 40 RFCs dedicated to IMS, e.g. tailoring IETFprotocols to IMS

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IMS step by stepDesigned for 3G UMTS networks

3G UMTS network

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3G UMTS network

GGSN (or a IP router)

IMS step by stepBut IMS works over IP (v6)

Voice, Video

IP Network

GGSNGateway from the

UMTS network toother networks

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3G UMTS network

IP Network

GGSN

CSCF (SIP proxy and registrar)

SIP signaling

IMS step by stepIMS is a infrastructure of SIP servers!

Voice, Video

slide 5

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3G UMTS network

GGSN

CSCF (SIP Proxy)

SIP signaling

IMS step by step!that can interact with some UMTS nodes

Voice, Video

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3G UMTS network

GGSN

CSCF (SIP Proxy)

SIP signaling

IMS step by stepMedia does not reach the IMS

Voice, Video

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3G UMTS network

GGSN

CSCF (SIP Proxy)

SIP signalingContains media

flows requirementsfor the network

(codecs, BW)

QoS in IMS: a scenarioTwo users want to setup a video call.

The video flow needs 128 kbps, the audio one 16 kbps

Media Flows

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3G UMTS network

GGSN

CSCF (SIP Proxy)



(codecs, BW)

QoS in IMS: a scenarioThe PCRF instructs the network to accommodate these flows

PCRF. Instructs

the network toaccommodatethe media flows

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3G UMTS network

GGSN

CSCF (SIP Proxy)



(codecs, BW)

QoS in IMS: a scenarioMedia flows traverse the network

Media Flows

PCRF. Instructs

the network toaccommodatethe media flows

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3G UMTS network

GGSN

CSCF (SIP Proxy)

SIP signaling

Charging in IMS: a scenarioTwo users want to setup a video call. One is

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3G UMTS network

GGSN

CSCF (SIP Proxy)

Charging in IMS: a scenariovideo audio flows consume network resources

Media Flows

GGSN is aware ofthese details (bytes

sent/ received)

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3G UMTS network

GGSN

CSCF (SIP Proxy)

Charging in IMS: a scenarioUMTS CDF/CGF gathers and correlates both data

Media Flows

CDF/CGF

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3G UMTS network

GGSN

S-CSCF

Authe. and Autho. in IMSDepends on 3G user control. SIP signaling proceeds only after contacting the HSS

HSSSIPSignaling

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