G.19 Emergency Service over IMS

34.229-13GPPInternet Protocol (IP) multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP)Part 1: Protocol conformance specificationRelease 16TSUser Equipment (UE) conformance specification

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

G.19.1 Emergency call with emergency registration / WLAN

G.19.1.1 Definition

Test to verify that the UE can correctly register to IMS emergency services and initiate an IMS emergency call over WLAN when UE is registered to IMS non-emergency services of the HPLMN either with ISIM or USIM.

G.19.1.2 Conformance requirement

[TS 24.229 Rel-14, annex R.2.2.6]:

In this release of the specification, a WLAN, conforming to the requirements in this annex, defines emergency bearers. Emergency session is supported over the WLAN access if the UE has failed or has not been able to use 3GPP access to set up an emergency session as described in 3GPP TS 23.167 [4B] Annex J.

…

EPC procedures for emergency session using WLAN are defined for both trusted WLAN access via S2a, depending on the TWAN usage mode, anduntrusted WLAN access via S2b to access EPC.

When the IM CN subsystem is selected as the domain for the emergency call attempt, and the UE uses:

– untrusted WLAN access via S2b, the UE determines that the EPC supports emergency bearer services by selecting or using an ePDG that has indicated its capability of support for emergency services, as specified in subclause 7.2.1A of 3GPP TS 24.302 [8U];

…

Once IPsec tunnel setup is completed, the UE shall follow the procedures described in subclause R.2.2.1 of this specification for establishment of IP-CAN bearer and P-CSCF discovery accordingly.

…

When the emergency session ends, the UE:

1) shall release the tunnel as described in 3GPP TS 24.302 [8U]; and

2) if EPC via WLAN is the preferred IP-CAN to access IM CN subsystem or if no 3GPP access is available:

a) if the UE did not select the currently selected ePDG using procedures for selection of ePDG for non-emergency services, shall select an ePDG for non-emergency services as described in 3GPP TS 24.302 [8U];

b) if the UE does not have an IP-CAN bearer for non-emergency SIP signalling, shall follow the procedures described in subclause R.2.2.1 for establishment of an IP-CAN bearer for SIP signalling and P-CSCF discovery; and

c) if the UE determines that its contact associated with the IP-CAN bearer for non-emergency SIP signalling is not bound to a public user identity, shall perform an initial registration as specified in subclause 5.1.1.2 using the IP-CAN bearer for SIP signalling.

[TS 24.302 Rel-14, clause 7.2.1A]:

The UE performs ePDG selection for emergency bearer services based on the ePDG configuration information provided by the home operator in the UE via H-ANDSF or via USIM, or via implementation specific means:

The ePDG configuration information used for selecting the ePDG for emergency bearer services includes:

– when available in ANDSF MO, Emergency_ePDG_Identifier and ePDG selection information are provisioned in ePDG node under Home Network Preference as specified in 3GPP TS 24.312 [13]; and

– when available in the USIM, the Emergency ePDG Identifier and ePDG selection information are provisioned in EF_ePDGIdEm and EF_{ePDGSelection} files as specified in 3GPP TS 31.102 [45].

NOTE: Implementation specific means apply only if the configurations via H-ANDSF and USIM are not present.

When performing ePDG selection for establishing emergency bearer services, the UE shall proceed by following the general ePDG selection procedure specified in subclause 7.2.1 except:

– Emergency_ePDG_Identifier shall be used instead of Home ePDG identifier;

– All ePDG FQDNs and visited country FQDNs for DNS query shall be constructed based on the ePDG FQDN format defined for emergency services as defined in 3GPP TS 23.003 [3]; and

– If the ME is not equipped with a UICC, the UE shall consider the ePDG configuration information as not available.

[TS 24.302 Rel-14, clause 7.2.5]:

If the UE needs to establish an IMS emergency session over untrusted non-3GPP access as specified in 3GPP TS 24.229 [67], the UE shall:

– if the UE is not connected to an ePDG yet, select an ePDG that supports emergency services as described in subclause 7.2.1A;

…

Once the UE selects an ePDG that supports emergency services as specified in subclause 7.2.1A, the UE shall initiate an IKEv2 tunnel establishment procedure towards this new ePDG as described in subclause 7.2.2.

G.19.1.3 Test purpose

1) To verify that the UE sends a correctly composed initial SIP REGISTER request for emergency services to S-CSCF via the discovered P-CSCF, according to 3GPP TS 24.229 [10] clause 5.1.6.1; and

2) To verify that the UE is able to use the IMS security procedures for the IMS emergency registration, as defined for IMS AKA and IPSec within 3GPP TS 24.229 [10] clause 5.1.1; and

3) To verify that the UE sends a correctly composed SIP INVITE request for the emergency call setup and will correctly complete the emergency session setup according to 3GPP TS 24.229 [10] clauses 5.1.6.8.3 and 6.1.2; and

4) To verify that at IMS emergency call release, the UE performs an initial IMS registration.

G.19.1.4 Method of test

Initial conditions

UE contains either ISIM and USIM applications or only USIM application on UICC. UE has activated the IP-CAN to the Evolved Packet Core (EPC) via Wireless Local Access Network (WLAN) with SS. The UE has registered to IMS over WLAN according to procedure C.2c.

Test procedure

0) UE executes the procedure described in TS 36.508 [94] Table 4.5A.24.3-1.

1-4) UE performs IMS emergency registration and IMS emergency speech call.

10-12) Call is released on the UE.

12A) The UE initiates a disconnection from the IPsec tunnel set up for the emergency session as defined in 36.508 [94] Table 4.5A.23A.3-1.

Expected sequence:

NOTE: Only the IMS procedure relevant to the test purpose is described below.

Step	Direction		Message	Comment
	UE	SS
1-4			Steps defined in clause C.20	IMS emergency registration by the UE
5-9			Steps defined in clause C.22	IMS emergency call setup with PSAP
10-12			Steps 1-3 defined in clause C.32	The UE releases the call
12A				IPsec tunnel disconnection procedure according to TS 36.508 [94] subclause 4.5A.23A.3

Specific Message Contents

INVITE (Step 5)

Use the default message “INVITE for MO call setup” in annex A.2.1 with condition A7 (INVITE for creating an emergency session within an emergency registration).

180 Ringing (Step 7)

Use the default message “180 Ringing for INVITE” in annex A.2.6 with condition A4 (180 sent by the SS when setting up an emergency call).

200 OK (Step 8)

Use the default message “200 OK for other requests than REGISTER or SUBSCRIBE” in annex A.3.1 with condition A6 (Response sent by SS for INVITE for emergency call).

G.19.1.5 Test requirements

The UE shall send requests and responses as described in clause G.19.1.4.

Annex H (normative): IP-Connectivity Access Network specific test cases when using xDSL, Fiber or Ethernet to access IM CN subsystem