This document defines the stage 2 service description for emergency services in the IP Multimedia Core Network Subsystem (IMS), including the elements necessary to support IP Multimedia (IM) emergency services and IM emergency services for eCall. ITU T Recommendation I.130  describes a three-stage method for characterisation of telecommunication services, and ITU T Recommendation Q.65  defines stage 2 of the method.
This document covers also the Access Network aspects that are crucial for the provisioning of IMS emergency services. Other 3GPP specifications that are related to the IMS emergency services are TS 23.228 on IMS in general, including fixed broadband access aspects, TS 23.060 describing GPRS (UTRAN): TS 23.401 describing EPS (UTRAN and E-UTRAN); TS 23.402 describing Non 3GPP access (WLAN) to EPC; TS 23.271 that covers location services; TS 23.216 and TS 23.237 describing Single Radio Voice Call Continuity (SRVCC) and Dual Radio Voice Call Continuity (DRVCC) for IMS Emergency session, TS 23.292 describing the use of IMS services when using CS access for the media bearer and TS 23.501 and TS 23.502 describing support of emergency services and location for 5GS. TS 25.301 contains an overall description of the UMTS Terrestrial Radio Access Network; TS 36.300 contains an overall description of the Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); and TS 38.300 contains an overall description of the Next Generation Radio Access Network (NG-RAN). Other non-3GPP specifications that are related to the IMS emergency services include 3GPP2 cdma2000 HRPD IP CAN, as specified in 3GPP2 X.S0060  when the UE is connected to a PDS core network and 3GPP2 X.S0057 A  when the UE is connected to an EPC core network.
The emergency support in different IP-CANs is described in the Informative Annex E.
The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
References are either specific (identified by date of publication, edition number, version number, etc.) or non specific.
For a specific reference, subsequent revisions do not apply.
For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.
ETSI TS 182 024 v.2.1.1: "Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); Hosted Enterprise Services; Architecture, functional description and signalling".
IEEE Std 802.11-2012: "IEEE Standard for Information technology--Telecommunications and information exchange between systems Local and metropolitan area networks--Specific requirements Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications".
For the purposes of the present document, the terms and definitions given in TR 21.905 and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905.
Charging Data Record:
Record generated by a network element for the purpose of billing a subscriber for the provided service. See TS 32.260 for further details.
Connectivity Session Location and Repository Function (CLF):
As per ETSI ES 282 004 , the Connectivity Session Location and Repository Function (CLF) registers the association between the IP address allocated to the UE and related network location information, i.e.: access transport equipment characteristics, line identifier (Logical Access ID), IP Edge identity.
NG-eCall (eCall Over IMS):
A manually or automatically initiated IMS emergency call, from a vehicle, supplemented with a minimum set of emergency related initial data (MSD).
Emergency Call Server (ECS):
The functional entity consists of a Location Retrieval Function (LRF) and either a routing proxy or a redirect server, e.g. an ECS contains a VPC and a Routing Proxy or Redirect Server in NENA I2 architecture .
The Emergency CSCF handles certain aspects of emergency sessions, e.g. routing of emergency requests to the correct emergency centre or PSAP.
Emergency Service Query Key (ESQK):
A 10-digit North American Numbering Plan number used to identify a particular emergency call instance. It is used by the LRF as a key to look up for the location information and callback information associated with the emergency call instance and is also used by the PSAP to query location information from the LRF.
North American Numbering Plan number used for routing of an emergency call to the appropriate gateway for an eventual delivery towards a CS-based PSAP.
Geographical Location Information:
Location indicated in geographical terms, for example geographical coordinates or street address (e.g. as supported by RFC 4119).
Condition defined by the authority whose legislation applies where the emergency service is invoked.
Information about the current location of the UE in the network. Location is indicated in network terms, for example using the global cell id in cellular networks, line-id in fixed broadband networks, (OMA-Location also uses this term, but OMA so far defines the Location Identifier only for cellular access.)
The location information may consist of the Location Identifier, and/or the Geographical location information.
Location Retrieval Function (LRF):
This functional entity handles the retrieval of location information for the UE including, where required, interim location information, initial location information and updated location information. The LRF may interact with a separate RDF or contain an integrated RDF in order to obtain routing information. The LRF may interact with a separate Location Server or contain an integrated Location Server in order to obtain location information. The LRF may interact with or contain other types of location server functions in order to obtain location information.
A number, which may be used in the event of network failure towards a specific location based PSAP or a number that can be associated to a national or default PSAP/Emergency centre.
Condition set by operator.
Private Numbering Plan:
According to ETSI TS 181 019 , a numbering plan explicitly relating to a particular private numbering domain.
Public Safety Answering Point (PSAP):
A physical location, where emergency calls from the public are received.
Routing Determination Function (RDF):
The functional entity, which may be integrated in a Location Server or in an LRF, provides the proper PSAP destination address to the E-CSCF for routing the emergency request. It can interact with a LS to manage ESQK allocation and management, and deliver location information to the PSAP.
For the purposes of the present document, the following terms and definitions given in TS 24.229 apply:
Private Network Traffic
Public Network Traffic
For the purposes of the present document, the following terms and definitions given in TS 23.401 apply:
eCall Only Mode: