3GPP 24.501 v20.0.0 — the document's own text

4.5.4.2 Access control and checking in 5GMM-CONNECTED mode and in 5GMM-CONNECTED mode with RRC inactive indication

When the UE is in 5GMM-CONNECTED mode or 5GMM-CONNECTED mode with RRC inactive indication, upon detecting one of events 1) through 8) listed in clause 4.5.1, the NAS shall categorize the corresponding access attempt into access identities and an access category following:

clause 4.5.2, table 4.5.2.1 and table 4.5.2.2, and clause 4.5.3, if the UE is not operating in SNPN access operation mode over 3GPP access ; or
clause 4.5.2A, table 4.5.2A.1 and table 4.5.2A.2, and clause 4.5.3, if the UE is operating in SNPN access operation mode over 3GPP access ,

and provide the access identities and the access category to the lower layers for the purpose of access control checking. In this request to the lower layer the NAS can also provide to the lower layer the RRC establishment cause determined as specified in clause 4.5.6 of this specification.

NOTE 1: As an implementation option, the NAS can provide the RRC establishment cause to the lower layers after being informed by the lower layers that the access attempt is allowed.

If the UE has uplink user data pending for one or more PDU sessions when it builds a REGISTRATION REQUEST or SERVICE REQUEST message for the access attempt, the UE shall indicate the respective PDU sessions in the Uplink data status IE as specified in clause 5.5.1.3.2 and 5.6.1.2, regardless of the access category for which the access barring check is performed.

NOTE 2: The UE indicates pending user data for all the respective PDU sessions, even if barring timers are running for some of the corresponding access categories.

If the lower layers indicate that the access attempt is allowed, the NAS shall take the following action depending on the event which triggered the access attempt:

if the event which triggered the access attempt was an MO-MMTEL-voice-call-started indication, an MO-MMTEL-video-call-started indication, an MO-SMSoIP-attempt-started indication, or an MO-IMS-registration-related-signalling-started indication, the NAS shall notify the upper layers that the access attempt is allowed;
if the event which triggered the access attempt was a request from upper layers to send a mobile originated SMS over NAS, 5GMM shall initiate the NAS transport procedure as specified in clause 5.4.5 to send the SMS in an UL NAS TRANSPORT message;
if the event which triggered the access attempt was a request from upper layers to establish a new PDU session, 5GMM shall initiate the NAS transport procedure as specified in clause 5.4.5 to send the PDU SESSION ESTABLISHMENT REQUEST message;
if the event which triggered the access attempt was a request from upper layers to modify an existing PDU session, 5GMM shall initiate the NAS transport procedure as specified in clause 5.4.5 to send the PDU SESSION MODIFICATION REQUEST message;
if the event which triggered the access attempt was a request to re-establish the user-plane resources for an existing PDU session, 5GMM shall initiate the service request procedure as specified in clause 5.6.1;
if the event which triggered the access attempt was an uplink user data packet to be sent for a PDU session with suspended user-plane resources, 5GMM shall consider that the uplink user data packet is allowed to be sent;
if the event which triggered the access attempt was a request from upper layers to send a mobile originated location request, 5GMM shall initiate the NAS transport procedure as specified in clause 5.4.5 to send an LCS message in an UL NAS TRANSPORT message; and
if the event which triggered the access attempt was a request from upper layers to send a mobile originated signalling transaction towards the PCF by sending an UL NAS TRANSPORT message including a UE policy container (see 3GPP TS 24.587 [19B] and 3GPP TS 24.554 [19E]), 5GMM shall initiate the NAS transport procedure as specified in clause 5.4.5 to send the signalling transaction via an UL NAS TRANSPORT message.

If the lower layers indicate that the access attempt is barred, the NAS shall take the following action depending on the event which triggered the access attempt:

if the event which triggered the access attempt was an MO-MMTEL-voice-call-started indication, an MO-MMTEL-video-call-started indication or an MO-SMSoIP-attempt-started indication, or an MO-IMS-registration-related-signalling-started indication:

if the UE is operating in the dual-registration mode, the UE may proceed in S1 mode with the appropriate EMM specific procedures and ESM procedures to make a PDN connection providing access to IMS available; see clause 4.8.3 and 3GPP TS 24.301 [15];
otherwise, the NAS shall notify the upper layers that the access attempt is barred. In this case, upon receiving an indication from the lower layers that the barring is alleviated for the access category with which the access attempt was associated, the NAS shall notify the upper layers that the barring is alleviated for the access category;

NOTE 3: In this case prohibiting the initiation of the MMTEL voice session, MMTEL video session or prohibiting sending of the SMS over IP or the IMS registration related signalling is performed by the upper layers.