The EU Emergency Services Workshop13-15 April 2011, Budapest, Hungary

ATIS/3GPP Common IMS Emergency Calling

Randall GellensQualcomm Incorporatedrandy@qualcomm.com

The EU Emergency Services Workshop13-15 April 2011, Budapest, Hungary

ATIS in Brief…

• Established in 1983, a technical planning and standards development organization committed to rapidly developing and promoting global technical and operations standards for the Information and Communications Technologies (ICT) industry.

• Uses a market-driven pragmatic, flexible and open approach to develop end-to-end, implementable, interoperable standards and a broad array of solutions.

• 250+ ATIS Member Companies Represent a Wide Cross Section of the Global Information, Entertainment, and Communications Industry.

– With more than 20 committees and over 600 participants, ATIS actively formulates worldwide technical and operations standards for the global ICT Industry

– The CTO/Senior Executive Level Board of Directors identifies priorities, needs and opportunities at the intersection of business and technology

• North American Organizational Partner for the 3rd Generation Partnership Project (3GPP), a member of and major contributor to the ITU-R/ITU-T, and a member of the Inter-American Telecommunication Commission (CITEL).

• Accredited by the American National Standards Institute (ANSI).

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The EU Emergency Services Workshop13-15 April 2011, Budapest, Hungary

ATIS/3GPP IMS EC Architecture

• IMS is upper-layer control-plane signaling

– Uses SIP

– Same for all access types (e.g., UMTS, eHRPD, LTE)

– Wireless and wired (i.e., fixed, nomadic, mobile)

– Supports authorization, charging, services, etc.

– Handles call setup and teardown (using SIP signaling)

– Handles media path allocation/deallocation

• Location determination may differ by access

– SUPL is User Plane and does not differ by access type

– Control Plane (CP) location differs by access type

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The EU Emergency Services Workshop13-15 April 2011, Budapest, Hungary

IMS Elements, Oversimplified

• User equipment (UE)• Call Session Control Functions (SIP proxies)

– Proxy-, Emergency-, Serving-, Interrogating-

• Various specialized functional elements– Location Retrieval Function (LRF)

• Includes Route Determination Function (RDF)

– Emergency Access Transfer Function (EATF)• Anchors media for Single Radio Voice Call Continuity (SRVCC) between

Circuit Switched (CS) and Packet Switched (PS) modes

– Media Gateway Control Function (MGCF) – for CS interworking– Media Gateway (MGW) – for CS interworking

• Home and visited (serving) networks– P-CSCF, E-CSCF, LRF, and EATF always in serving network for

emergency calls

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The EU Emergency Services Workshop13-15 April 2011, Budapest, Hungary

IMS Emergency Call Architecture

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from 3GPP TS 23.167 11.0.1 2011-01-04

LRF

P-CSCF E-CSCF UE

S-CSCF

from PSAP Le (e.g. E2)

to PSAP (via PSTN via BGCF/

MGCF)

MI

Mm/Mx

to PSAP or ECS (via IBCF/IP multimedia Network)

Mi/Mg

Mw

Mw

Mm/Mx/Mw from PSAP

EATF

I4

I5 from I-CSCF

Mw

Gm

Mx/Mw

From private network via

IBCF/I-CSCF

ISC/Mw

From AS

The EU Emergency Services Workshop13-15 April 2011, Budapest, Hungary

ESInetTermination

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Architecture for IMS w/ Location

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• VPLMN contains 3GPP and OMA architecture elements• ESInet contains NENA i3 architecture elements• VPLMN-to-ESInet interfaces are being evaluated by ATIS• UE and internal VPLMN interfaces are defined by 3GPP and OMA

UE eNodeB

ServingGateway

PDNGateway

MME P-CSCF E-CSCF

S-CSCF

VPLMN (Visited Public Land Mobile Network)

LRF

GMLC

SLP

ESRP

ECRF

i3PSAP

Voice/data

E-SMLC

Control Plane (CP) LCS Signaling

SUPL LCS Signaling

SIP related signaling

ESRP Emergency Services Routing Proxy

ESInet

ECRF Emergency Call Routing Function

Not yet defined

The EU Emergency Services Workshop13-15 April 2011, Budapest, Hungary

Call Flow Example

UE P-CSCF E-CSCF ESRP PSAP

SIP INVITE

SIP 200 OK

Exchange media in the User Plane

Session setup and initial media exchange

Emergency registration (depending on circumstances)

Retrieve location

Retrieve route

SIP INVITE with emergency indication

SIP BYE

Session and mediaRelease

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S-CSCF

ESInetIMS Network

The EU Emergency Services Workshop13-15 April 2011, Budapest, Hungary

3GPP IMS Emergency Call Status

• Release 9: Supports IP based emergency calls for voice and can support

Real Time Text (e.g. using TTY if there is handover to the CS domain)

• Release 10: Enhancements added to support emergency calls using

private numbering in an Enterprise network

• Release 11 and later:– Non-Voice Emergency Services (NOVES)

– Improved support for location by reference is expected

– Network-provided cell ID for more reliable PSAP routing is expected

• ATIS:– North American (NA) specific standards to augment 3GPP IMS solution

• E.g., define portions that are left to national variation or need more detail

• WTSC Issue P0030: “Implementation of 3GPP Common IMS Emergency Procedures for IMS Origination and ESInet/Legacy Selective Router Termination”

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The EU Emergency Services Workshop13-15 April 2011, Budapest, Hungary

Differences from IETF ECRIT (1)

• IMS Originating device

– Performs emergency registration (unless UE knows it is in home network and already registered)

– Does not need to obtain own location

– No provision for performing LoST query

– Only SUPL and/or CP support required for location for mobile UE

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The EU Emergency Services Workshop13-15 April 2011, Budapest, Hungary

Differences from IETF ECRIT (2)

• Originating IMS network– Must be capable of performing position determination

• Since originating device may not supply location

• May choose to validate a location supplied by device

– How location is delivered to PSAP• Location-by-value vs. location-by-reference

– Route determination (especially for mobile)• Not specified in 3GPP (no mention currently of ECRF)

• ATIS is expected to specify for North America

– Support for delivering calls to ESInet (SIP/IMS) and legacy CS

– No LIS• LRF performs location dereference function (resolve location URI)

• No mechanism for originating device to obtain own location

• Location validation function (for fixed) not in scope for ATIS

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The EU Emergency Services Workshop13-15 April 2011, Budapest, Hungary

Thank You

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The EU Emergency Services Workshop13-15 April 2011, Budapest, Hungary

Abbreviations

• CP: Control Plane

• CS: Circuit Switched

• E-CSCF: Emergency Call Session Control Function

• EATF: Emergency Access Transfer Function

• E-SMLC: Evolved Serving Mobile Location Server

• eHRPD: Evolved High-Rate Packet Data

• EVDO: Evolution – Data Optimized

• HRPD: High-Rate Packet Data

• GMLC: Gateway Mobile Location Center

• I-CSCF: Interrogating Call Session Control Function

• IMS: IP Multimedia Subsystem

• IP: Internet Protocol

• MGCF: Media Gateway Control Function

• MGW: Media Gateway

• LTE: Long-Term Evolution

• LRF: Location Retrieval Function

• P-CSCF: Proxy Call Session Control Function

• PS: Packet Switched

• RDF: Route Determination Function

• S-CSCF: Serving Call Session Control Function

• SIP: Session Initiation Protocol

• SLP: SUPL Location Platform

• SUPL: Secure User-Plane Location

• UE: User Equipment

• UMTS: Universal Mobile Telephone Service

• UP: User Plane

• VCC: Voice-Call Continuity

• VPLMN: Visited Public Land Mobile Network

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The EU Emergency Services Workshop13-15 April 2011, Budapest, Hungary

Backup Slides

• Call flows in more detail

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The EU Emergency Services Workshop13-15 April 2011, Budapest, Hungary

LRF

P-CSCF E-CSCF UE

S-CSCF

from PSAP Le (e.g. E2)

to PSAP (via PSTN via BGCF/

MGCF)

MI

Mm/Mx

to PSAP or ECS (via IBCF/IP multimedia Network)

Mi/Mg

Mw

Mw

Mm/Mx/Mw from PSAP

EATF

I4

I5 from I-CSCF

Mw

Gm

Mx/Mw

From private network via

IBCF/I-CSCF

ISC/Mw

From AS

Generalized Call Flow

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The EU Emergency Services Workshop13-15 April 2011, Budapest, Hungary

Ingress attributes

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LRF

P-CSCF E-CSCF UE

S-CSCF

from PSAP Le (e.g. E2)

to PSAP (via PSTN via BGCF/

MGCF)

MI

Mm/Mx

to PSAP or ECS (via IBCF/IP multimedia Network)

Mi/Mg

Mw

Mw

Mm/Mx/Mw from PSAP

EATF

I4

I5 from I-CSCF

Mw

Gm

Mx/Mw

From private network via

IBCF/I-CSCF

ISC/Mw

From AS

• Directory Number• MDN/MSISDN• Cell ID

• maybe: L-by-V (PIDF-LO)• maybe: L-by-R (Location URI, pANI, etc.)

The EU Emergency Services Workshop13-15 April 2011, Budapest, Hungary

Location Retrieval

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LRF

P-CSCF E-CSCF UE

S-CSCF

from PSAP Le (e.g. E2)

to PSAP (via PSTN via BGCF/

MGCF)

MI

Mm/Mx

to PSAP or ECS (via IBCF/IP multimedia Network)

Mi/Mg

Mw

Mw

Mm/Mx/Mw from PSAP

EATF

I4

I5 from I-CSCF

Mw

Gm

Mx/Mw

From private network via

IBCF/I-CSCF

ISC/Mw

From AS

• Cell Site Location• Lat/Lon Location• Civic Location

The EU Emergency Services Workshop13-15 April 2011, Budapest, Hungary

LRF

P-CSCF E-CSCF UE

S-CSCF

from PSAP Le (e.g. E2)

to PSAP (via PSTN via BGCF/

MGCF)

MI

Mm/Mx

to PSAP or ECS (via IBCF/IP multimedia Network)

Mi/Mg

Mw

Mw

Mm/Mx/Mw from PSAP

EATF

I4

I5 from I-CSCF

Mw

Gm

Mx/Mw

From private network via

IBCF/I-CSCF

ISC/Mw

From AS

RDF

Routing Determination

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• ESRK/ESQK• PSAP URI

(Routing URI)

The EU Emergency Services Workshop13-15 April 2011, Budapest, Hungary

LRF

P-CSCF E-CSCF UE

S-CSCF

from PSAP Le (e.g. E2)

to PSAP (via PSTN via BGCF/

MGCF)

MI

Mm/Mx

to PSAP or ECS (via IBCF/IP multimedia Network)

Mi/Mg

Mw

Mw

Mm/Mx/Mw from PSAP

EATF

I4

I5 from I-CSCF

Mw

Gm

Mx/Mw

From private network via

IBCF/I-CSCF

ISC/Mw

From AS

Call Delivery

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• Directory Number• ESRK/ESQK• PIDF-LO• Location URI

The EU Emergency Services Workshop13-15 April 2011, Budapest, Hungary

LRF

P-CSCF E-CSCF UE

S-CSCF

from PSAP Le (e.g. E2)

to PSAP (via PSTN via BGCF/

MGCF)

MI

Mm/Mx

to PSAP or ECS (via IBCF/IP multimedia Network)

Mi/Mg

Mw

Mw

Mm/Mx/Mw from PSAP

EATF

I4

I5 from I-CSCF

Mw

Gm

Mx/Mw

From private network via

IBCF/I-CSCF

ISC/Mw

From AS

Location acquisition

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E2, HELD

← DN, ESRK, ESQK, URI

→ E2 format, PIDF-LO