ESIFs Role in Defining IMSbased Emergency Services

1
ESIFs Role in Defining IMS-based Emergency
Services

• Bob Sherry

July 18, 2007
2
NG Emergency Service Definition

• NENA
• i3 TID and Stage 2 Infrastructure
• Stage 2 Includes References to IMS
• 3GPP/3GPP2
• Defining Emergency Services in Originating
  Network
• IETF
• Defining SIP-based protocols
• Other Protocols LoST, HELD, etc.
• No Body Defining Architecture and Stage 3 of an
  IMS-based Emergency Services Network

3
Potential ATIS/ESIF Role

• Define IMS-based Emergency Service Network
  Architecture and Stage 3
• Based Upon NENA Requirements and Stage 2
• Based upon 3GPP Effort Relating to Originating
  Networks.
• Based upon IETF Protocols
• Incorporate Access From Legacy and NG Originating
  Networks

4
IMS Home Network Functional Elements

• Home Subscriber Server
• Centralized DB
• HLR successor
• User profile
• Filter criteria (sent to S-CSCF)
• Which applications
• Which conditions

• Application Servers
• Push-to-talk
• Instant messaging
• Telephony AS
• 3rd party or IMS Vendor

• Media Resource Function Controller
• Pooling of Media servers (e.g. conference)

Domain Name Server
Home Network
UA/UE
P-CSCF
SIP
HSS
DNS ENUM

• Media GatewayControl Function
• Interfaces to PSTN/PLMN by
• Converting SIP lt-gt ISUP
• Interworking RTP to circuit
• H.248 control of MGW

Diameter
SIP
MRFC
I-CSCF
S-CSCF
P-CSCF
SIP
SIP
UA/UE
SIP
MS
MS
SIP
SIP
SIP
MGCF
BGCF
SIP
ISUP

• Call Session
• Control Function
• SIP registration
• SIP session setup

SIP
SS7
H.248
PSTN
MGW
RTP
TDM

• Serving CSCF
• Registrar
• Session control
• Application Interface

• Proxy CSCF
• 1st contact point for UA
• QoS
• Routes to S-CSCF

Foreign Network

• Interrogating CSCF
• Entry point for incoming calls
• Determines S-CSCF for Subscribers
• Hides network topology

• Breakout Gateway Control Function
• Selects network (MGCF or other BGCF) in which
  PSTN/ PLMN breakout is to occur

5
Emergency Services in 3GPP Originating Network

• UE
• Initiates Emergency Call
• P-CSCF
• Recognizes Emergency Call and Forwards to E-CSCF
• E-CSCF
• Interrogates Location Retrieval Function (LRF)
  for Routing Instructions
• Routes call to PSAP
• LRF
• May Retrieve Location (left to implementation)
• Determines PSAP URI (Routing Determination
  Function (RDF) left to implementation)
• S-CSCF
• Used for Call Back
• PSAP
• May be IP-based or Legacy

6
3GPP Incorporating Reference to NENA i2 In Orig
Network- Redirect

• Emergency Call Initiated
• Emergency Call Forwarded to Emergency Call Server
  (ECS)
• Emergency Call Server uses i2 procedures to
  determine PSAP and redirects back to E-CSCF.
  (VPC-like)
• E-CSCF routes call to Media Gateway. Normal call
  set up through Selective Router. (Or may route to
  a IP capable PSAP).
• .

7
3GPP Incorporating Reference to NENA i2 In Orig
Network- Proxy

• Emergency Call Initiated
• Emergency Call Forwarded to Emergency Call Server
  (ECS)
• Emergency Call Server uses i2 procedures to
  determine PSAP. ECS uses i2 procedures to route
  call to Media Gateway (VPC-like)
• Normal call set up through Selective Router
• .

8
EIMS From PTSC Liaison
I-CSCF/IBCF
Other IP Network
Mx
Le
I-BGF
Mx
Web Services
Cx
I-S/BC
ISC
P-CSCF
IP Bearer
Gm
Mi
Mw
BGCF
PSAP UE
Mj
Mr
MGCF/SGW
PSTN/Legacy Emergency Services Network
Gm
MRFC
SS7 PCM Trunks
A-BGF
IP Access Network
A-S/BC
T-MGF
MRFP
PSTN GW
MS
Calling UE
IP Bearer
Note S-CSCF is not illustrated since it is
outside the scope.
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Potential ATIS EIMS Architecture (OLD)
SIP
Le
Web Services
Mx
Cx
ISC
Gm
SS7 PCM Trunks
Mi
Mw
Mr
Other (TBD)
SIP
Diameter
Bearer
Cx
Mx
Mw
Mi
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EIMS Interfaces

• Takes Advantage of Defined 3GPP Network Elements
  and Interfaces
• Based upon IETF Protocols
• Incorporates Routing upon Location (Emergency
  Call Routing Function (ECRF), RDF, LRF)
• Incorporates Location Acquisition (LIS)
• Introduces Policy Routing (Time of Day, etc.)
• Defines Protocols and Interfaces left to
  Implementation in 3GPP.
• Leverages Existing Work in PTSC, Other ATIS
  committees