SIP in 3GPP
August 12th, 2000
Adam Roach
adam.roach@ericsson.com
Disclaimer
Some terms used in this presentation are
trademarks or registered trademarks of their
respective owners. The use of these terms is
not an endorsement of the related product or
corporation; the terms are included only to give
the audience concrete example with which they
are (hopefully) already familiar.
3GPP Network Model
Alternative
Acces
s
Network
Legacy
mobile
Network
Applications &
Services *)
SCP
Mh
CAP
Iu
UTRAN
MT
R
Uu
Mr
EIR
Gf
Mg
MRF
Gi
Gc
Gi
MGCF
GGSN
SGSN
Iu
MGW
MGW
Nb
Mc
Nc
GMSC server
CAP
CAP
PSTN/
Legacy/External
Mc
MSC server
Applications
& Services *)
T-SGW *)
Mc
Gi
Gn
Iu
IP Multimedia Domain
(multimedia by SIP,
IETF RFC2543)
CSCF
CSCF
Gi
PS Domain
TE
Mm
Cx
HSS *)
Gr
Multimedia
IP Networks
CSCF
R-SGW *)
Mw
Ms
D
C
HSS *)
R-SGW *)
Mh
T-SGW *)
CS Domain
(multimedia by ITU H.324M)
Different Kinds of CSCFs
Home A
Home B
HSS
8
HSS
7
9
S-CSCF
6
I-CSCF
14
10
4
5
S-CSCF
I-CSCF
15
16
13
17
Visited B
2
Visited A
P-SCSF
11
3
P-CSCF
12
18
GGSN
SGSN
GGSN
SGSN
Radio Access Network
Radio Access Network
B
A
1
Proxy CSCF:
Provides
emergency
service
breakout,
triggers for
locallyprovided
services, and
number
normalizing
(per local
dialing plan)
Different Kinds of CSCFs
Home A
Home B
HSS
8
HSS
7
9
S-CSCF
6
I-CSCF
14
10
4
5
S-CSCF
I-CSCF
15
16
13
17
Visited B
2
Visited A
P-SCSF
11
3
P-CSCF
12
18
GGSN
SGSN
GGSN
SGSN
Radio Access Network
Radio Access Network
B
A
1
Interrogating
CSCF:
Queries the
HSS to find
the correct SCSCF. First
point of
contact for
incoming
call
signalling.
Different Kinds of CSCFs
Home A
Home B
HSS
8
HSS
7
9
S-CSCF
6
I-CSCF
14
10
4
5
S-CSCF
I-CSCF
15
16
13
17
Visited B
2
Visited A
P-SCSF
11
3
P-CSCF
12
18
GGSN
SGSN
GGSN
SGSN
Radio Access Network
Radio Access Network
B
A
1
Serving
CSCF:
Provides
subscriber
services.
3GPP SIP Decisions
• SIP from terminal to network
• SIP between network call nodes
General Principles
• S-CSCFs may have different capabilities.
• Firewalling must be possible.
• Terminal and node behaviours should be consistent,
regardless of whether the user is roaming.
• Follow IETF standards as much as possible.
• Service nodes are access independent.
• Serving CSCFs may reside in either home or roamed-to
network.
(Ideal) Access Independent Network
Worldcom
Pay-per-view movie
service using RTSP,
hosted by backbone
provider
Yahoo!
Service
Node
PSTN GW owned by traditional
telco. Calling users subscribe;
authorization/billing based on
challenge/response model
Service
Node
Service
Node
Peer IP
backbone
networks
IP
IP
IP
PSTN
IP
GGSN
SGSN
CMTS
Broadband Access
Providers (Wireless,
Cable, DSL, etc.)
Service
Node
My own machine with
a multicast chat
server for all my
friends, connected
through my
broadband access
Short Term Network Picture
Access
Access
IP
PSTN
Firewall
PSTN
Firewall
IP
Call
Control
IP
Backbone
Call
Control
Access
IP
Firewall
Firewall
Call
Control
Call
Control
PSTN
IP
PSTN
Access
Selection of Serving
Node Location
(Home Execution)
Home
HSS
Profile
Location
3
4
6
7
8. OK
S-CSCF
I-CSCF
5. REGISTER
2. REGISTER
9. OK
Visited
P-CSCF
1. REGISTER
10. OK
GGSN
SGSN
Radio Access Network
Selection of Serving
Node Location
(Non-Roaming)
Home
HSS
Profile
Location
3
4
6
7
8. OK
S-CSCF
I-CSCF
5. REGISTER
2. REGISTER
9. OK
P-CSCF
1. REGISTER
10. OK
GGSN
SGSN
Radio Access Network
Home
HSS
Profile
Location
3
4
5. REGISTER
I-CSCF
12. OK
9
2. REGISTER
10
13. OK
11. OK
Visited
S-CSCF
I-CSCF
8. REGISTER
6
7
P-CSCF
HSS
14. OK
Location
Profile
1. REGISTER
GGSN
SGSN
Radio Access Network
Selection
of Serving
Node
Location
(Visited
Execution)
Visited-Domain
Provided Service
(e.g. 411 Directory
Assitance)
HSS
4
3
5. INVITE
S-CSCF
6. INVITE
I-CSCF
14. 200
2. INVITE
sip:info@visited
13. 200
Visited
10. IAM
MGCF/
T-SGW
11. ANM
PSTN
9. INVITE
I-CSCF
15. 200
12. 200
7
8
MGW
P-CSCF
16. 200
HSS
GGSN
SGSN
Radio Access Network
Updates
URI
1. INVITE tel:1411
Non-Conversational Services
Web
Server
IP
Backbone
Media
Server
GGSN
SGSN
Radio Access Network
Future Issues to be Decided
• Handling of Instant Messages (SMS). SIP
“MESSAGE” seems a natural fit, but other ideas
are being proposed
• Uses of MRF (Media Resource Function) node.
Possible uses include:
– Conference Bridge (both dial-in and spontaneous)
– Transcoding
– Streaming Media/Announcments
Wireless Services Implications
Called
Home
Caller
Home
Value added
services
Value added
services
API
API
SIP
(S-CSCF)
Access
signaling
SIP
(S-CSCF)
signaling
Access
WireLin
e
WLan
UTRAN
WireLin
e
WLan
TA?
GPRSTA?
GPRS
FW?
Bearer Services
oriented
Video/Audio/Signaling
IP backbone
TA?
UTRAN
FW?
Bearer Services
Bearer Services
oriented
oriented
Video/Audio/Signaling
Conclusions
• 3G is dedicated to using SIP for call control.
• This development will allow a seamless
integration of “smart” wireless terminals into the
exploding information/communication IP
networks.
• If deployed correctly, the transition to 3G
networks will be a revolution in wireless
communications unlike any previously seen.