12.2a MO Call with preconditions at both originating UE and terminating UE – 504 Server Time-out

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

12.2a.1 Definition

When the S-CSCF is temporarily unable to process an INVITE for an MO call with preconditions as the S-CSCF does not have the user profile or does not trust the data that it has (e.g. due to restart), the S-CSCF can reject the request by returning a 504 (Server Time-out) response to the UE with specific content as specified in 3GPP TS 24.229 [10] clause 5.4.3.2. As a result the UE will initiate restoration procedures by performing an initial registration.

12.2a.2 Conformance requirement

In the event the UE receives a 504 (Server Time-out) response containing:

1) a P-Asserted-Identity header field set to a value equal to a URI:

a) from the Service-Route header field value received during registration; or

b) from the Path header field value received during registration; and

2) a Content-Type header field set according to subclause 7.6 (i.e. "application/3gpp-ims+xml"), independent of the value or presence of the Content-Disposition header field, independent of the value or presence of Content-Disposition parameters, then the default content disposition, identified as "3gpp-alternative-service", is applied as follows:

a) if the 504 (Server Time-out) response includes an IM CN subsystem XML body as described in subclause 7.6 with the <ims-3gpp> element, including a version attribute, with the <alternative-service> child element:

a) with the <type> child element set to "restoration" (see table 7.7AA); and

b) with the <action> child element set to "initial-registration" (see table 7.7AB);

then the UE:

– shall initiate restoration procedures by performing an initial registration as specified in subclause 5.1.1.2; and

– may provide an indication to the user based on the text string contained in the <reason> child element of the <alternative-service> child element of the <ims-3gpp> element.

Reference(s)

3GPP TS 24.229 [10], clause 5.1.2A.1.6

12.2a.3 Test purpose

To verify that when the UE receives a 504 (Server Time-out) response to an INVITE request for an MO call with preconditions containing a P-Asserted-Identity header field set to a value equal to a URI from the Service-Route header field value received during registration and the rest of the message is set as described in [10] subclause 5.1.2A.1.6, then the UE initiates restoration procedures by performing an initial registration as specified in [10] subclause 5.1.1.2.

12.2a.4 Method of test

Initial conditions

UE contains an ISIM and USIM or only USIM application on the UICC. UE has activated a PDP context/EPS bearer, discovered P-CSCF and registered to IMS services, by executing the generic test procedure in Annex C.2 up to the last step.

SS is configured with the shared secret key of IMS AKA algorithm, related to the IMS private user identity (IMPI) configured on the UICC card equipped into the UE. SS has performed AKAv1-MD5 authentication with the UE and accepted the registration (IMS security). UE is configured to use the precondition mechanism.

Test procedure applicable for a UE with E-UTRA support (TS 34.229-2 [5] A.18/1)

1-8) UE executes the procedures described in TS 36.508 [94] table 4.5A.6.3-1 steps 1 to 8.

9) The SS responds with a 504 (Server Time-out) response.

10) The SS waits for the UE to send an ACK to acknowledge the reception of 504 (Server Time-out) response.

11-18) As specified in steps 4-11 annex C.2.

Expected sequence

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

Step	Direction		Message	Comment
	UE	SS
1-2			Steps 1-2 defined in annex C.21	MTSI MO speech call. Referred from 36.508 [94] table 4.5A.6.3-1 for a UE with E-UTRA support.
3	🡨		504 Server Time-out	Set as per the specific message contents.
4	🡪		ACK
5-12	🡪		Steps 4-11 defined in annex C.2	The UE performs an initial registration.

NOTE: The default messages contents in annex A are used with condition “IMS security” or “GIBA” when applicable.

Specific Message Contents

Steps 1-2

As specified in annex C.21

504 Server Time-out (Step 3)

Use the default message “504 Server Time-out” in Annex A.4.6

ACK (Step 4)

As specified in annex A.2.7.

Steps 5-12

As specified in annex C.2.

12.2a.5 Test requirements

After step 3 the UE shall perform an initial registration.