7.1 MTSI MO Voice Call / 503 Service Unavailable / 5GS

34.229-53GPPInternet Protocol (IP) multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP)Part 5: Protocol conformance specification using 5G System (5GS)Release 16TSUser Equipment (UE) conformance specification

7.1.1 Test Purpose (TP)

(1)

with { UE being registered to IMS and UE having sent an initial INVITE request for MO Voice call }

ensure that {

when { UE receiving a 503 Service Unavailable response containing a Retry-After header indicating a period of 20 seconds }

then { UE does not reattempt the request until after the indicated period }

}

(2)

Void

7.1.2 Conformance Requirements

The conformance requirements covered in the present test case are, unless otherwise stated, Rel-15 requirements.

[TS 24.229, clause 5.1.3.1]:

Upon receiving a 503 (Service Unavailable) response to an initial INVITE request containing a Retry-After header, then the originating UE shall not automatically reattempt the request until after the period indicated by the Retry-After header contents.

[TS 24.229, clause 6.1.2]:

An INVITE request generated by a UE shall contain a SDP offer and at least one media description. This SDP offer shall reflect the calling user’s terminal capabilities and user preferences for the session.

…

NOTE 2: If the originating UE does not use the precondition mechanism (see subclause 5.1.3.1), it will not include any precondition information in the SDP message body.

7.1.3 Test description

7.1.3.1 Pre-test conditions

System Simulator:

– 1 NR Cell connected to 5GC, default parameters.

UE:

– The UE contains either ISIM and USIM applications or only USIM application on UICC.

– The UE is configured to register for IMS after switch on.

– The UE is either configured to use preconditions or to not use preconditions or does not support preconditions..

Preamble:

– UE is in state 1N-A and registered to IMS

7.1.3.2 Test procedure sequence

Table 7.1.3.2-1: Main Behaviour

St

Procedure

Message Sequence

TP

Verdict

U – S

Message

1

UE is made to attempt an IMS voice call

–

–

–

–

2-7

Steps 2-7 of generic procedure specified in Table 4.9.15.2.2-1 of TS 38.508-1 [21] are performed.

–

–

–

–

–

EXCEPTION: In parallel with Step 8, parallel behaviour defined in table 7.1.3.2-2 takes place

–

–

–

–

–

EXCEPTION: Steps 8a to 8b describe behaviour that depends on UE configuration; the “lower case letter” identifies a step sequence that takes place if such configuration was conducted.

–

–

–

–

8a

IF the UE is configured to use preconditions THEN step1 of Annex A.4.1 takes place.

–>

INVITE

–

–

8b

ELSE step 1 of Annex A.4.2 takes place.

–>

INVITE

–

–

9

SS sends 503 (Service Unavailable) with Retry-After header indicating a period of 20 seconds.

<–

503 Service Unavailable

–

–

10

UE acknowledges the reception of 503 (Service Unavailable) message.

–>

ACK

–

–

11

The SS starts timer t_Waits=20s.

–

–

–

–

12

Check: Does the UE reattempt the INVITE request?

–>

INVITE

1

F

13

The SS waits for expiry of t_Waits.

–

–

–

–

–

EXCEPTION: Steps 14a1 to 14b8 happen if the UE choses to reattempt the INVITE request, i.e., these steps are optional. The SS waits at most 30 more seconds for such INVITE request before it terminates the test case.

–

–

–

–

–

EXCEPTION: Steps 14a1 to 14b11 describe behaviour that depends on UE configuration; the “lower case letter” identifies a step sequence that takes place if such configuration was conducted.

–

–

–

–

14a1-14a5

IF the UE is configured to use preconditions THEN steps 1 to 5 of Annex A.4.1 take place.

–

–

–

–

14a6

Step 10 of generic procedure specified in Table 4.9.15.2.2-1 of TS 38.508-1 [21] is performed.

–

–

–

–

–

EXCEPTION: In parallel to steps 14a7 and 14a8 below, step 14a9 occurs.

–

–

–

–

14a7-14a8

Steps 11-12 of generic procedure specified in Table 4.9.15.2.2-1 of TS 38.508-1 [21] are performed.

–

–

–

–

14a9-14a15

steps 6 to 12 of Annex A.4.1 take place

–

–

–

–

14b1-14b5

ELSE steps 1 to 5 of Annex A.4.2 takes place

–

–

–

–

14b6-14b8

Steps 10-12 of generic procedure specified in Table 4.9.15.2.2-1 of TS 38.508-1 [21] are performed.

–

–

–

–

14b9-14b11

Steps 6 to 8 of Annex A.4.2 take place

–

–

–

–

Table 7.1.3.2-2: Parallel behaviour

St

Procedure

Message Sequence

TP

Verdict

U – S

Message

1

The UE transmits an RRCReconfigurationComplete message.

–>

NR RRC: RRCReconfigurationComplete

–

–

7.1.3.3 Specific message contents

Table 7.1.3.3-1: 503 Service Unavailable (step 9, table 7.1.3.2-1)

Derivation path: TS 34.229-1 [2], Annex A.4.2

Header/param

Cond

Value/remark

Rel

Reference

Retry-After

delta-seconds

20