IMS

1
IMS Workshop
Clayton Cruz Expert IP Networks Softswitch
2
IMS Workshop Módulo 1

• ALL IP Vision Network Transformation
• 3GPP Evolution from R99 to R7
• ETSI TISTPAN
• Emulation concept
• Simulation concept
• SAE LTE
• Business Introduction to IMS
• IMS Concepts
• Subscriber identification
• SIM, USIM ISIM
• P-CSCF discovery
• Registration
• Service Profile
• Initial Filter Criteria
• IMS and GPRS Roaming

3
IMS Workshop Módulo 2

• IMS  Architecture Details
• S-CSCF
• P-CSCF
• I-CSCF
• E-CSCF
• MGCF
• MGw
• MRFP
• MRFC
• BGCF
• SBG
• SEG
• ENUM
• AGCF PES
• .etc
• IMS Reference Points Interfaces
• Gm
• Mw

4
IMS Workshop Módulo 3

• SIP
• Introduction to SIP
• Protocol Stack
• SIP Logical Entities
• SIP Methods
• SDP
• SIP for 3GPP
• Private Header Extensions
• SIP Call Flows

5
IMS Workshop Módulo 4

• Introduction to IPv6
• IPv4 and IPv6 Interworking in IMS
• IMS QoS (evolution towards PCC)
• IMS Security
• Access Security AKA
• Network Security
• Ericsson IMS CORE Roadmap Products
• IMS Common System
• IMT
• IMS AS

6
IMS architecture
Based on IETF, 3GPP , OMA and TISPAN
specifications
OSA/Parlay appl. environment
ISC
Sh
xxx AS
NRG
Support
DNS ENUM
Open SIP AS environment
POTS access interworking
Charging
IMS-service to POTS access
SDS/IMS Studio
AGCF (P-CSCF)
IMS core
Sh (Diameter)
HSS
ISC
SIP
H.248 (AGW)
SIP Applications Enablers
Sh
Messaging
GLMS
Presence
Cx (Diameter)
RTP
MSAN
ISC
CSCF (P-,I-, S-)
Broadband IMS access
Broadband access
Multi- media Telephony
Push To Talk
IPCentrex
WeShare
A-RACS
Mr (SIP)
Rq
SIP
Mp
SGC (P-CSCF)
SGC
IP network inter-working
SIP
Mp
H.248
A-SBG
SGC (I-BCF)
H.248
E.g. BRAS
802.1x
MP
MP (A-BGF)
H.248
SIP/H.323
N-SBG
WLAN
WSN
Media Servers
MRFP
MP (I-BGF)
Cellular access
Cellular IMS access
SIP
Rx
PCRF (PDF)
P-CSCF
RTP, MSRP,
GSM
GSM
Gx
RAN
RAN
Gb
/ IP
CS network inter-working
BSC
BSC
RTP
H.248
SIP
SIP
SGSN
GGSN
IP
RTP
Gn
ISUP
WCDMA
WCDMA
RNC
RNC
Iu
Iu
-
-
ps
ps
/IP
/IP
RAN
RAN
RTP, MSRP,
CCS
H.248
PDSN
GRX interwork
HA
BSC
BSC
GSTN
MGW
N-SBG
CDMA
CDMA
RAN
RAN
7
IMS Workshop Módulo 1
ALL-IP Vision Network Transformation
8
What do we mean by All-IP
All services are based on IP technology
Common service control is handled by IMS (SIP
signaling)
All transport of user data and control signaling
is done using IP
A multitude of IP access methods supporting IP
connectivity
9
Evolution Cycle towards ALL IP Mobile Operators
Simplified View
CS migration to MSS
IMS
3G Rollout
SAE LTE
ALL IP
10
Evolution Cycle towards ALL IP Mobile Operators
Detailed View
Telecom Quality IP Backbone is required from this
point
Circuit Switched Core
CS interworking with IMS for VoiP and Video Via
MSS
MSS SIGTRAN VToIP
Common CORE 2G 3G
MSS migration to MGCF and IM-MGW
CS migration to MSS
Packet Switched Core
Migration to SAE Including support for Non 3GPP
Access
Service Aware Control Charging
Common CORE 2G 3G
IMS Support For Basic Services
ALL IP Tranport (ie. Gb)
Access
IP RAN
3G HSPA
LTE
ALL IP
IMS CORE
IMS CORE Basic Services
IMS CORE Mass deployment VoIP
11
Evolution Cycle towards ALL IP Fixed Operators
Simplified View
IMS introduction
Broadband Rollout
Modernization with NGN
MSAN, VDSL2, GPON, etc
Technology Througput (DL)
ADSL 2 M
ADSL2 25 M
VDSL2 100 M
DOCSIS3 160 M
GPON 2,5 Gbps
ALL IP
12
IMS Workshop Módulo 1
3GPP R99 R7
13
IMS Related Standardization Bodies
AS
Multimedia Telephony
IP
GSM/W-CDMA Access to IMS
Wireline Access to IMS

• QoS policy control
• Emergency call (location)
• LIS

• QoS policy control
• Emergency call (location)
• LIS

Mobile
SME
Residential
14
3GPP Release Timeline
HSDPA
HSPA
HSUPA
WCDMA
MBMS
FBI
IMS
MSC Split
I-WLAN
VCC
Rel 7 (target)
2007
2008
1999
2000
2001
2002
2003
2004
2005
2006
15
3GPP Release 99 Architecture
Other PLMNs
HLR
PSTN/ Legacy/ External
SGSN
Gn
Gp
Gn/Gp
Gb
BSS/ GERAN
SGSN
GGSN
TE
MT
R
Um
Iu
E
TE
MT
UTRAN
MSC
GMSC
R
Uu
Iu
MAP
Applications Services
Signalling and/or data
Signalling
HLR
16
3GPP Release 4 Architecture
Other PLMNs
HLR
PSTN/ Legacy/ External
SGSN
Gn
Gp
Gn/Gp
Gb
BSS/ GERAN
SGSN
GGSN
TE
MT
R
Um
Iu
Nb
TE
MT
UTRAN
MGw
MGw
R
Uu
Mc
Nc
MSC server
GMSC server
Applications Services
MAP
Signalling and/or data
Mh
MAP
SGW
HLR
Signalling
17
3GPP Release 5 architecture
Multimedia IP Networks
Applications Services
Other Access Networks
CSCF
Mw
Mm
CAP
Cx
Gi
Other PLMNs
HSS
CSCF
Mg
SGSN
Gr
Mr
Gi
Gc
Gn
EIR
MGCF
SGW
MRF
Gp
Gf
Gi
Nb
Gb
BSS/ GERAN
SGSN
GGSN
TE
MT
PSTN/ Legacy/ External
Mc
Gi
R
Um
Iu
Nb
TE
MT
UTRAN
MGW
MGW
R
Uu
Iu
Mc
Mc
Nc
MSC server
GMSC server
Signalling and/or data
Applications Services
MAP
Signalling
Mh
MAP
SGW
HLR
18
3GPP R5 System ArchitectureTS 23.002 V5.12.0
19
3GPP R5 System ArchitectureTS 23.002 V5.12.0
20
3GPP Release 6 architecture
Other Legacy Mobile network
Multimedia IP Networks
Applications Services
C, D
IMS-ALG TrGW
CSCF
Mw
Sh
Ch
Mm
Cx
Gi
Other PLMNs
HSS
Mi
CSCF
Dx
BGCF
Gi
Mg
SGSN
Gr
Mr
SLF
Mj
Gq
Gc
Gn
PDF
EIR
MGCF
SGW
MRF
Gx
Gp
Gf
Mn
Gi
Gn
Gb
BSS/ GERAN
SGSN
GGSN
TE
MT
PSTN/ Legacy/ External
IM-MGW
Gi
R
Um
Iu
Mb
Nb
TE
MT
UTRAN
MGW
MGW
R
Uu
Iu
EIR
Mc
Mc
Wa
Gf
3GPPAAA
Nc
WLAN Access Netw.
GMSC server
MSC server
WLAN UE
Wn
Ww
Wg
Wm
D
C
Signalling and/or data
Wx
WAG
Wp
Mh
Wu
Signalling
PDG
HSS
SGW
21
3GPP R6 IMS architecture(TS 23.002)
22
Tunnel Termination Gateway
Wm

• TTG provides PDG functionality, tradditionally
  not included GGSN
• Gn is a subset of the Gn interface

PDG
Tunnel Termination Gateway
Wi/Gi
GGSN
Wu
Gn
23
InterworkingArchitecture as defined in 29.163
Mj
BGCF
BICC/ISUP over SCTP/IP
SGW
MGCF
CSCF
Mg
BICC/ISUP over MTP
Mn
BICC over SCTP/IP
CS channels e.g. PCM
Mb
CS network
IM-MGW
GGSN
User Plane
Control Plane
24
IMS History (Industry dimension)
First commercial deployment
25
3GPP Rel-5

• Enabling basic multimedia end to end call
• IMS architecture
• A 3GPP SIP profile is defined
• Includes
• IMS AKA using REGISTER method
• UE-UE session set-up for a multimedia call
• A number of private extensions(mainly for 3GPP)
• Diameter profile
• Policy SBLP, Go-interface
• Security architecture

26
3GPP Rel-6

• Service enablers, Enhancements and Improvements
• Presence and Group management enabler
• Conferencing enabler
• Messaging enabler
• Early IMS deployment
• IPv4 (interworking between IPv4 and IPv6 is
  described)
• Single Sign On
• Multiple Private Ids per Public Id
• Inter-working IMS and CS domains

27
3GPP Rel-7 Items

• Multimedia Telephony supplementary services,
  TISPAN R1 based
• PCC policy and charging control (Merge of SBLP
  and FBC architectures)
• Media Resource (MRF) H.248 profile
• Enhanced Real-time Communication (Characteristics
  improvements)
• Emergency call
• Voice Call Continuity (CS to IMS(WLAN) service
  continuity)

28
IMS Workshop Módulo 1
TISPAN R1 R2
29
ETSI/TISPAN NGN Standardization

• TISPAN is responsible for all aspects of
  standardization for present and future converged
  networks, including the NGN (Next Generation
  Network) in ETSI.
• TISPAN has decided to use IMS as base, and the
  additional specifications will be incorporated
  into 3GPP.
• TISPAN NGN R1 specifications were released in Dec
  2005.

Telecommunication and Internet converged Services
and Protocols for Advanced Networking
30
TISPAN NGN R1 - overview
Applications
NNI
Streaming Services (RTSP-based)
Based on 3GPP IMS
IP connectivity access network and related
functionality
PSTN/ISDN Emulation
UNI
Other Networks
Network Access Attachment Functions NASS
Resource and Admission Control Function RACS
GW
GW
Access Transport Network
Core Transport Network
3GPP IP CAN
31
Common Components of TISPAN R1

• A Common component can be accessed by more than
  one subsystem.
• Two types can be identified
• Component known in 3GPP IMS
• New component, defined by TISPAN
• Components known in 3GPP IMS
• Subscription Locator Function (SLF)
• Application Server Function (ASF)
• Interconnection Border Control Function (IBCF)
• User Profile Server Function (UPSF) (subset of
  the HSS)
• Charging and Data Collection Functions
• New components defined by TISPAN
• Application Server Function (ASF) with itf to
  RACS
• Inter-working Function (IWF)
• Charging and Data Collection Functions with it-f
  to IBCF

32
TISPAN R2Synchronisation of Specifications with
3GPP

• Alignment of the timescales and dependencies of
  TISPAN R1 with the work in 3GPP Release 7 on FBI.
• Alignment of the timescales of TISPAN R2 with the
  ongoing work in 3GPP Release 8 and FMC.
• Objective Single core solution based on
• IMS Core signalling technology
• Multiple access technologies in cooperation with
  3GPP
• ADSL
• WLAN via xSDL
• 3GPP CAN (GPRS, WLAN via GPRS, etc..).
• Ongoing discussions within TISPAN, 3GPP and other
  groups.

33
Fixed Core Network EvolutionEmulation x
Simulation
PSTN Emulation

PSTN Emulation over IMS Same user experience
PSTN Simulation Enhanced user experience
34
PSTN/ISDN Simulation vs Emulation
Simulation
SIP
RTP
SIP
Tispan PSTN Emulation
RTP
Z -
H.248
Softswitch PSTN Emulation
Full Z
PSTN _at_ IP network
MGW
PSTN _at_ TDM
MGW
35
Introduction of softswitching
Local Application
Transit and IGW application
NGN core
TeS
TeS
ISUP/INAP SIP-I, SIP, SIP/H.323,
SGw
Other PSTN/PLMN Network
H.248
DSS1 V5 RSS
SS (SIP-I) Network
TDM access
IMS Networks
Packet access
H.248
SIP / H.323 VoIP Networks
36
Complement telephony softswitch with IMS for new
services
Local Application
Transit and IGW application
NGN core
TeS
TeS
ISUP/INAP SIP-I, SIP, SIP/H.323,
SGw
Other PSTN/PLMN Network
H.248
DSS1 V5 RSS
SS (SIP-I) Network
TDM access
IMS Networks
Packet access
H.248
SIP / H.323 VoIP Networks
37
Grow IMS and start migrate customers
Local Application
Transit and IGW application
NGN core
TeS L-AGCF
ISUP/INAP SIP-I, SIP, SIP/H.323,
SGw
Other PSTN/PLMN Network
H.248
DSS1 V5 RSS
SS (SIP-I) Network
TDM access
IMS Networks
Packet access
H.248
SIP / H.323 VoIP Networks
38
Telephony softswitch becomes an enhancement to IMS
Local Application
Transit and IGW application
NGN core
IBCF/IWF
MGCF/SGF
AGCF
ISUP/INAP SIP-I, SIP, SIP/H.323,
SGw
Other PSTN/PLMN Network
SS (SIP-I) Network
IMS Networks
Packet access
H.248
SIP / H.323 VoIP Networks
39
IMS Workshop Módulo 1
SAE LTE
40
What is SAE, LTE and HSPA?

• SAE System Architecture Evolution (Packet Core)
• LTE Long Term Evolution (LTE RAN)
• HSPA HSPA Evolution (3G RAN)

2G
CS networks
Circuit Core
3G
IMS
Packet Core
LTE
Non-3GPP
IP networks
41
Mobile Networks Evolution

• Radio Side (LTE Long Term Evolution)
• Improvements in spectral efficiency, user
  throughput, latency
• Simplification of the radio network
• Efficient support of packet based services MBMS,
  IMS, etc.
• Network Side (SAE System Architecture
  Evolution)
• Improvement in latency, capacity, throughput
• Simplification of the core network
• Optimization for IP traffic and services
• Simplified support and handover to non-3GPP
  access technologies

42
Evolving to LTE
HSDPA High Speed Downlink Packet Access HSPA
High Speed Packet Access MBMS
Multicast/Broadcast Multimedia Service LTE Long
Term Evolution
43
3GPP Packet Core architecture(SAE simplified, as
of Sept 2006) TS 23.882
44
LTE / SAE

• Flat 2-node architecture for optimized payload
  path
• Simple QoS model
• Low delays (10ms)
• High Bandwidth (100M, 50M)

IMS multimediaservices
GW
GW
AGW
IP/Ethernet
LTE
LTE
LTE
Note GW corresponds to 3GPP anchorSAE
anchorUPE
45
Migration for a 3GPP operator2007 starting
point
Services
GGSN
Mobile Edge
SGSN
RNC
RNC
46
Migration for a 3GPP operator2007/08
optimizing for Mobile Broadband

• Packet Core One Tunnel solution
• SGSN acting as Server for 3G
• Evolution of HSPA
• Deployment of IMS

IMS multimediaservices
GGSN
Mobile Edge
SGSN
RNC
RNC
47
Migration for a 3GPP operator2009/10 LTE
introduction

• LTE RAN introduced to further boost mobile
  broadband capabilities
• GGSN (and SGSN) evolving into AGW (UP/CP)

IMS multimediaservices
AGW
Mobile Edge
UP
Non-3GPP access
SGSN/AGW
RNC
CP
RNC
48
IMS Workshop Módulo 1
BUSINESSINTRODUCTION TO IMS
49
Operator business model
Walled garden
Channel provider
Bit-Pipe
content applications
own 3rd party content applications
3rd party content applications
proprietaryservice layer (SL)
Open Controlled SL
3rd party SL
transport backbone
transport backbone
transport backbone
Operator Business area
Enterprise
Residential
Mobile
IMS is designed to develop the Operator Business
Model
50
IMS the way forward

• IMS, IP Multimedia Subsystem, is a main future
  architecture
• for operators offering end-user services in
  the packet domain
• IMS is a generic architecture for offering
• multimedia services (not just VoIP)
• IMS is defined in 3GPP/3GPP2 standards.
• Embraced in ETSI TISPAN
• IMS is delivering services over multiple
• access networks
• IMS is a service Enabler !!!!

51
Why IMS - End User perspective
Pre-IMS Communication
Voice
Chat
Instant Messaging
Video Telephony

• 1 gt Decide on communication mode/media
• 2 gt Create content
• 3 gt Send/call the chosen person
• 4 gt Disconnect and reconnect if changing media

IMS enables the Super-Store Principle
52
Why IMS Operator Perspective (1)

• How important is IMS to your companys business
  strategy?
• Light Reading Insider
• February 2006

53
Why IMS Operator Perspective (2)
54
IMS by Expert..

• All IMS services can be done without
  IMS
• This is true! Other technologies can be used.
  The end-user probably doesnt care about the
  enabling technologies
• However Without IMS, service creation can be
  complex, and expensive to the operator and the
  user
• The key is integrating different services (e.g.,
  multimedia, presence, instant messaging, web
  browsing, location, personalised services) within
  a single technology

55
IMS Workshop Módulo 1
IMS Concepts Overview
56
Identification of users

• The home network operator allocates one or more
  public user identities to each user
• The home network operator allocates one private
  user identity to each user

57
Private user identities

• The home network operator allocates exactly one
  private user identity to each user
• A private user is not a URI
• A private user identity has the format of the
  Network Access Identifier (NAI).
• The ISIM stores the private user identity. The
  user cannot modify that identity.
• The home network authenticates the private user
  identity (during registration)
• The home network verifies that a public user
  identity is allocated to a private user identity

58
NAI - RFC 2486
IANA -gt Those wishing to use an NAI realm name
should first acquire the rights to use the
corresponding FQDN
nai username / ( username "_at_" realm )
username dot-string realm realm "." label
label let-dig (ldh-str) ldh-str ( Alpha
/ Digit / "-" ) let-dig dot-string string / (
dot-string "." string ) string char / ( string
char ) char c / ( "\" x ) .........
IF NOT ISIM ltIMSIgt_at_ims.mncltMNCgt.mccltMCCgt.3gppnetwo
rk.org.
fred_at_3com.com red_at_foo-9.com fred_smith_at_big-co.co
m fred_at_bigco.com nancy_at_eng.bigu.edu
fred_at_foo fred_at_foo_9.com _at_howard.edu
fred_at_bigco.com_at_smallco.com engnancy_at_bigu.edu
59
Public user identities

• The home network operator allocates one or more
  public user identities to each user
• A public user identity can be either
• A SIP URI. Example sipclayton.cruz_at_ericsson.
  com
• A TEL URL. Example tel[phone]
• The ISIM stores at least one public user
  identity. The user cannot modify that identity.
• The user can register one more public user
  identities simultaneously, through a procedure
  called Implicit public user identity
  registration.
• The home network does not use the public user
  identity for authentication

60
Derived Private and Public Indentity
IMSI in use 724020999999999 where MCC
123 MNC 45
Private user identity 724020999999999_at_ims.mnc45.
mcc123.3gppnetwork.org
Public User Identity Sip724020999999999_at_ims.mn4
5.mcc123.3gppnetwork.org
61
Private Public Idendities

• Relationship of private and public user
  identities
• Each Public user identity is associated with one
  and only one Service Profile.
• Each service profile is associated with one or
  more Public user identities.
• The Service Profile is a collection of service
  and user related data.
• All Service Profiles that share the same Private
  user identity are associated to the same S-CSCF.

62
Identification of Network Nodes
All nodes handling SIP routing shall have an
identity using a Valid SIP URI It is not
mandatory to publish those SIP URI on DNS.
63
UICC

• UICC is the physical smart card in the UE
• USIM is the first UICC application for the
  subscriber based on IMSI and MSISDN, using 3GPP
  AKA authentication algorithm

UE
UICC
USIM
64
UICC, USIM and ISIM

• ISIM is the new UICC application for the IMS
  subscriber defined for the first 3GPP Release 5.
• ISIM is recommended, but not required for IMS.
• The necessary data can be shared or derived from
  the IMSI stored in the USIM.

UE
UICC
USIM
ISIM
65
Service Profile

• Collection of user-specific information
  permanently stored in the HSS
• Transfered to S-CSCF during Server assingment
  procedure (Cx interface) with SAA command
• Carried in one Diameter AVP
• Service profile is composed by
• Public Identification
• Service Authorization
• Filter Criteria

66
Initial Filter Criteria

• Filter Criteria is downloaded from HSS only
  during registration.
• S-CSCF shall apply filter criteria to determine
  the need to forward SIP request to AS.
• XML Modeling is defined in 3GPP TS 29.228
• FC is valid only throughout the registration
  lifetime or until the user profile is changed
• When S-CSCF receives an initial SIP request it
  evaluates the FC one by one. If the FC matches
  the S-CSCF proxies the SIP request to the right
  AS

67
Link in of application servers
No service or session state are passed between
application servers
An AS is unaware of the existence of other ASs,
and whether these will be linked in
User profile is retrieved from HSS upon
registration, which includes Initial Filter
Criteria
SIP-AS
SIP-AS
SIP-AS
HSS
S-CSCF
Initial Filter criteria govern the forwarding of
SIP messages to one or several application
servers. SIP messages or associated responses are
routed back toS-CSCF
P-CSCF
I-CSCF
68
Registration to the network
UE
IMS
GSN
HLR
69
Initial registration
UE
P-CSCF
S-CSCF
I-CSCF
SLF/ HSS
ME
ISIM
1. SIP REGISTER
2. SIP REGISTER
3. Diameter UAR
4. Diameter UAA
5. SIP REGISTER
6. Diameter MAR
7. Diameter MAA
8. SIP 401
9. AUTHENTICATE command
10. AUTHENTICATE response
11. SIP REGISTER
12. SIP REGISTER
13. Diameter UAR
14. Diameter UAA
15. SIP REGISTER
70
Initial registration
UE
P-CSCF
S-CSCF
I-CSCF
SLF/ HSS
ME
ISIM
16. Diameter SAR
17. Diameter SAA
18. SIP 200
71
IMS Roaming based on GPRS
72
IMS Roaming
73
More Technical Information
Wait for Módulo 2 or
74
Thank you !!! Clayton Cruz Expert IP Networks
Softswitch clayton.cruz_at_ericsson.com
75
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