C.2 Application usage of SIP

24.3903GPPRelease 17Stage 3TSUnstructured Supplementary Service Data (USSD) using IP Multimedia (IM) Core Network (CN) subsystem IMS

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

C.2.1 Procedures at the UE

C.2.1.1 3GPP PS data off

C.2.1.1.1 General

The UE may support the 3GPP PS data off.

If the UE supports the 3GPP PS data off:

1) the UE can be configured with up to two indications whether the USSI is a 3GPP PS data off exempt service, one indication is valid for the UE camping in the HPLMN or the EHPLMN, and the other indication is valid for any VPLMN the UE is roaming in; and

2) the UE may support being configured with the indications whether the USSI is a 3GPP PS data off exempt service using one or more of the following methods:

a) the EF_{3GPPPSDATAOFF} file described in 3GPP TS 31.102 [18];

b) the USSI_exempt node of 3GPP TS 24.391 [13], if the UE is in the HPLMN or the EHPLMN; and

c) the USSI_roaming_exempt node of 3GPP TS 24.391 [13], if the UE is in the VPLMN.

If the UE is configured with both the USSI_exempt node of 3GPP TS 24.391 [13] and the EF_{3GPPPSDATAOFF} file described in 3GPP TS 31.102 [18], then EF_{3GPPPSDATAOFF} file shall take precedence.

If the UE is configured with both the USSI_roaming_exempt node of 3GPP TS 24.391 [13] and the EF_{3GPPPSDATAOFF} file described in 3GPP TS 31.102 [18], then EF_{3GPPPSDATAOFF} file shall take precedence.

When the UE is only configured with the indication valid for the UE camping in the HPLMN or the EHPLMN, the UE shall use this indication also when the UE is in the VPLMN.

C.2.1.1.2 Enforcement

If the 3GPP PS data off status is "active", and the UE is not configured with indication that USSI is a 3GPP PS data off exempt service:

1) the UE shall terminate according to 3GPP TS 24.229 [6] any SIP dialog established according to subclause 4.5.4 or subclause 4.5.5 with a UE’s contact address containing an IP address associated with a GPRS IP-CAN bearer;

2) the UE shall not invoke the procedures in subclause 4.5.4 with a UE’s contact address containing an IP address associated with a GPRS IP-CAN bearer; and

NOTE 1: If the UE doesn’t invoke the procedures in subclause 4.5.4 due to conditions as described in bullet 2, the UE can attempt a request for an equivalent service via the CS domain – if supported and available – and, otherwise, the UE can attempt the service according to 3GPP TS 24.229 [13] and as described in subclause 4.5.4 via non-3GPP access.

3) if the UE registered a binding with IM CN subsystem, such that:

a) the contact address of the binding contains an IP address associated with a GPRS IP-CAN bearer; and

b) the Contact header field of the binding contains the g.3gpp.nw-init-ussi media feature tag;

then:

a) the UE shall de-register the binding of a UE’s contact address containing an IP address associated with a GPRS IP-CAN bearer from IM CN subsystem according to 3GPP TS 24.229 [6]; or

b) the UE shall re-register the binding of a UE’s contact address containing an IP address associated with a GPRS IP-CAN bearer with IM CN subsystem with a Contact header field not including the g.3gpp.nw-init-ussi media feature tag according to 3GPP TS 24.229 [6].

NOTE 2: Which of the bullets a), and b) the UE performs is influenced by other 3GPP PS data off exempt services.

C.2.2 Procedures at the USSI AS

C.2.2.1 3GPP PS data off

An USSI AS supporting the 3GPP PS data off can be configured with up to two values of whether USSI is a 3GPP PS data off exempt service, one value is valid for non-roaming users, and the other value is valid for users roaming in the various VPLMNs with whom roaming agreements exist.

When the USSI AS is only configured with the indication whether USSI is a 3GP PS data off exempt service for the UE camping in the HPLMN or the EHPLMN, the USSI AS shall use this indication also when the UE is in the VPLMN.

If the USSI AS supports the 3GPP PS data off, the USSI AS shall support obtaining registration state information from a received third-party SIP REGISTER request including information contained in the body of the third-party SIP REGISTER request as specified in 3GPP TS 24.229 [6], of the served UE.

If a received registration state information of the served UE indicates a Contact header field with the g.3gpp.ps-data-off media feature tag with the "active" value, and the USSI AS is not configured with indication that USSI is a 3GPP PS data off exempt service for the served UE then the USSI AS shall not invoke the procedures in subclause 4.5.5 which send a SIP request towards a contact address (or via a registration flow) of the served UE such that the contact address (or the registration flow) was registered or re-registered by a SIP REGISTER request with a P-Access-Network-Info header field with "3GPP-GERAN","3GPP-UTRAN", "3GPP-E-UTRAN" or "3GPP-NR" access class and with the "network-provided" header field parameter.

Annex D (normative):
IP-Connectivity Access Network specific concepts when using EPS to access IM CN subsystem