Content for  TS 24.501  Word version:  19.0.0

The purpose of the network-requested PDU session release procedure is to enable the network to release a PDU session or the user-plane resources on a single access of an MA PDU session.

In order to initiate the network-requested PDU session release procedure, the SMF shall create a PDU SESSION RELEASE COMMAND message. The SMF shall set the 5GSM cause IE of the PDU SESSION RELEASE COMMAND message to indicate the reason for releasing the PDU session. The 5GSM cause IE typically indicates one of the following 5GSM cause values: If the selected SSC mode of the PDU session is "SSC mode 2" and the SMF requests the relocation of SSC mode 2 PDU session anchor with different PDU sessions as specified in TS 23.502, the SMF shall include 5GSM cause #39 "reactivation requested". If the selected SSC mode of the PDU session is "SSC mode 2" or "SSC mode 1", the S-NSSAI or the mapped S-NSSAI of the PDU session needs to be replaced, the SMF shall include the Alternative S-NSSAI IE and 5GSM cause #39 "reactivation requested" in the PDU SESSION RELEASE COMMAND message. If the selected SSC mode of the PDU session is "SSC mode 2" or "SSC mode 1", replaced S-NSSAI is available and the SMF determines that the PDU session needs to be re-established on the replaced S-NSSAI, the SMF shall include 5GSM cause #39 "reactivation requested" and the replaced S-NSSAI in the PDU SESSION RELEASE COMMAND message. If the network-requested PDU session release procedure is triggered by a UE-requested PDU session release procedure, the SMF shall set the PTI IE of the PDU SESSION RELEASE COMMAND message to the PTI of the PDU SESSION RELEASE REQUEST message received as part of the UE-requested PDU session release procedure and shall not include the Access type IE in the PDU SESSION RELEASE COMMAND. If the network-requested PDU session release procedure is not triggered by a UE-requested PDU session release procedure, the SMF shall set the PTI IE of the PDU SESSION RELEASE COMMAND message to "No procedure transaction identity assigned". If the PDU session ID included in PDU SESSION RELEASE COMMAND message is associated with one or more multicast MBS sessions and either the Access type IE is not included or the Access type IE indicates "3GPP access", the SMF shall consider the UE as removed from the associated multicast MBS sessions. Based on the local policy and user's subscription data, if the SMF decides to release the PDU session after determining:

1. the UE has moved between a tracking area in NB-N1 mode and a tracking area in WB-N1 mode;
2. the UE has moved between a tracking area in NB-S1 mode and a tracking area in WB-N1 mode;
3. the UE has moved between a tracking area in WB-S1 mode and a tracking area in NB-N1 mode; or
4. a PDU session is not only for control plane CIoT 5GS optimization any more,

the SMF shall:

1. include the 5GSM cause value #39 "reactivation requested" in the 5GSM cause IE of the PDU SESSION RELEASE COMMAND message; or
2. include a 5GSM cause value other than #39 "reactivation requested" in the 5GSM cause IE of the PDU SESSION RELEASE COMMAND message.

If the SMF receives UE presence in LADN service area from the AMF indicating that the UE is out of the LADN service area and the SMF decides to release the PDU session, the SMF shall include the 5GSM cause value #46 "out of LADN service area" in the 5GSM cause IE of the PDU SESSION RELEASE COMMAND message. Upon receipt of the 5GSM cause value #46 "out of LADN service area" in the 5GSM cause IE of the PDU SESSION RELEASE COMMAND message, the UE shall release the PDU session. The SMF may include a Back-off timer value IE in the PDU SESSION RELEASE COMMAND message when the 5GSM cause value #26 "insufficient resources" is included in the PDU SESSION RELEASE COMMAND message. If the 5GSM cause value is #26 "insufficient resources" and the PDU SESSION RELEASE COMMAND message is sent to a UE configured for high priority access in selected PLMN or SNPN or the request type was set to "initial emergency request" or "existing emergency PDU session" for the establishment of the PDU session, the network shall not include a Back-off timer value IE. The SMF may include a Back-off timer value IE in the PDU SESSION RELEASE COMMAND message when the 5GSM cause value #67 "insufficient resources for specific slice and DNN" is included in the PDU SESSION RELEASE COMMAND message. If the 5GSM cause value is #67 "insufficient resources for specific slice and DNN" and the PDU SESSION RELEASE COMMAND message is sent to a UE configured for high priority access in selected PLMN or SNPN or the request type was set to "initial emergency request" or "existing emergency PDU session" for the establishment of the PDU session, the network shall not include a Back-off timer value IE. The SMF may include a Back-off timer value IE in the PDU SESSION RELEASE COMMAND message when the 5GSM cause #69 "insufficient resources for specific slice" is included in the PDU SESSION RELEASE COMMAND message. If the 5GSM cause value is #69 "insufficient resources for specific slice" and the PDU SESSION RELEASE COMMAND message is sent to a UE configured for high priority access in selected PLMN or SNPN or the request type was set to "initial emergency request" or "existing emergency PDU session" for the establishment of the PDU session, the network shall not include a Back-off timer value IE. The SMF should include a Back-off timer value IE in the PDU SESSION RELEASE COMMAND message when the 5GSM cause value #29 "user authentication or authorization failed" is included in the PDU SESSION RELEASE COMMAND message. If the service-level-AA procedure is triggered for the established PDU session for UAS services with re-authentication purpose, and the SMF is informed by the UAS-NF that UUAA-SM is unsuccessful or if the SMF receives UUAA revocation notification message from the UAS-NF as described in TS 23.256, the SMF shall transmit the PDU SESSION RELEASE COMMAND message to the UE, including:

1. the service-level-AA response in the Service-level-AA container IE, with the SLAR field set to the value of "Service level authentication and authorization was not successful or service level authorization is revoked"; and
2. the 5GSM cause value #29 "user authentication or authorization failed" in the 5GSM cause IE of the PDU SESSION RELEASE COMMAND message.

If the PDU session was established for C2 communication and the SMF is informed by UAS-NF that C2 authorization is revoked, the SMF shall include:

1. the service-level-AA response with the value of the C2AR field set to the "C2 authorization was not successful or C2 authorization is revoked" in the service-level-AA container IE of the PDU SESSION RELEASE COMMAND message, and
2. the 5GSM cause value #29 "user authentication or authorization failed" in the 5GSM cause IE of the PDU SESSION RELEASE COMMAND message.

The SMF shall send:

1. the PDU SESSION RELEASE COMMAND message; and
2. the N1 SM delivery skip allowed indication:
   1. if the SMF allows the AMF to skip sending the N1 SM container to the UE and the 5GSM cause IE is not set to #39 "reactivation requested"; or
   2. if the SMF allows the AMF to skip sending the N1 SM container to the UE and the Access type IE is not included

towards the AMF, and the SMF shall start timer T3592 (see example in Figure 6.3.3.2.1).

For a single access PDU session, upon receipt of a PDU SESSION RELEASE COMMAND message and a PDU session ID, using the NAS transport procedure as specified in subclause 5.4.5, the UE considers the PDU session as released and the UE shall create a PDU SESSION RELEASE COMPLETE message. For an MA PDU session, upon receipt of the PDU SESSION RELEASE COMMAND message, the UE shall behave as follows:

1. if the PDU SESSION RELEASE COMMAND message includes the Access type IE and the MA PDU session has user-plane resources established on both 3GPP access and non-3GPP access, the UE shall consider the user-plane resources on the access indicated in the Access type IE as released and shall create a PDU SESSION RELEASE COMPLETE message. If the Access type IE indicates "3GPP access" and there is one or more multicast MBS sessions associated with the MA PDU session, the UE shall locally leave these associated multicast MBS sessions;
2. if the PDU SESSION RELEASE COMMAND message includes the Access type IE and the MA PDU session has user-plane resources established on only the access indicated in the Access type IE, the UE shall consider the MA PDU session as released and shall create a PDU SESSION RELEASE COMPLETE message; and
3. if the PDU SESSION RELEASE COMMAND message does not include the Access type IE, the UE shall consider the MA PDU session as released and shall create a PDU SESSION RELEASE COMPLETE message.

If the UE is configured with on-demand S-NSSAI including slice deregistration inactivity timer:

1. if the PDU session associated with an on-demand S-NSSAI is released and there are no established user plane resources of an MA PDU session associated with this on-demand S-NSSAI and there is no PDU session associated with this on-demand S-NSSAI, the UE shall start the slice deregistration inactivity timer for this on-demand S-NSSAI over the corresponding access type;
2. if the MA PDU session associated with an on-demand S-NSSAI is released:
   for each registered access type, if there is no PDU session associated with this on-demand S-NSSAI and there are no established user plane resources of an MA PDU session associated with this on-demand S-NSSAI over the registered access type, the UE shall start the slice deregistration inactivity timer for this on-demand S-NSSAI over the corresponding registered access type; or
3. if the user plane resources of an MA PDU session associated with on-demand S-NSSAI is released over the access type and there is no PDU session associated with this on-demand S-NSSAI and there is no established user plane resources of an MA PDU session associated with this on-demand S-NSSAI over the corresponding access type, then UE shall start the slice deregistration inactivity timer over the corresponding access type.

If there is one or more multicast MBS sessions associated with the PDU session the UE considers as released, the UE shall locally leave these associated multicast MBS sessions. If the PDU SESSION RELEASE COMMAND message contains the PTI value allocated in the UE-requested PDU session release procedure, the UE shall stop the timer T3582. The UE should ensure that the PTI value assigned to this procedure is not released immediately. While the PTI value is not released, the UE regards any received PDU SESSION RELEASE COMMAND message with the same PTI value as a network retransmission (see subclause 7.3.1). If the PDU SESSION RELEASE COMMAND message includes 5GSM cause #39 "reactivation requested", then after completion of the network-requested PDU session release procedure, the UE should re-initiate the UE-requested PDU session establishment procedure as specified in subclause 6.4.1 for:

1. the PDU session type associated with the released PDU session;
2. the SSC mode associated with the released PDU session;
3. the DNN associated with the released PDU session; and
4. the S-NSSAI associated with (if available in roaming scenarios) a mapped S-NSSAI if provided in the UE-requested PDU session establishment procedure of the released PDU session. If the PDU SESSION RELEASE COMMAND message contains the Alternative S-NSSAI IE, the UE shall include both the S-NSSAI to be replaced and the alternative S-NSSAI during the UE-requested PDU session establishment procedure.

If the PDU SESSION RELEASE COMMAND message is received without the Back-off timer value IE or includes 5GSM cause #39 "reactivation requested", and the UE provided an S-NSSAI during the PDU session establishment, the UE shall stop timer T3585 if it is running for the S-NSSAI of the PDU session. If the UE did not provide an S-NSSAI during the PDU session establishment and the request type was different from "initial emergency request" and different from "existing emergency PDU session", the UE shall stop the timer T3585 associated with no S-NSSAI if it is running. If the PDU SESSION RELEASE COMMAND message was received for an emergency PDU session, the UE shall not stop the timer T3585 associated with no S-NSSAI if it is running. The timer T3585 to be stopped includes:

1. in a PLMN:
   1. the timer T3585 applied for all the PLMNs and for the access over which the PDU SESSION RELEASE COMMAND is received, if running;
   2. the timer T3585 applied for all the PLMNs and for both 3GPP access type and non-3GPP access type, if running;
   3. the timer T3585 applied for the registered PLMN and for the access over which the PDU SESSION RELEASE COMMAND is received, if running; and
   4. the timer T3585 applied for the registered PLMN and for both 3GPP access type and non-3GPP access type, if running; or
2. in an SNPN:
   1. the timer T3585 applied for all the equivalent SNPNs and for the access over which the PDU SESSION AUTHENTICATION COMMAND message is received, associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running;
   2. the timer T3585 applied for all the equivalent SNPNs and for both 3GPP access type and non-3GPP access type, associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running;
   3. the timer T3585 applied for the registered SNPN and for the access over which the PDU SESSION AUTHENTICATION COMMAND message is received, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and
   4. the timer T3585 applied for the registered PLMN and for both 3GPP access type and non-3GPP access type, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.

If the PDU SESSION RELEASE COMMAND message is received without the Back-off timer value IE or includes 5GSM cause #39 "reactivation requested", and the UE provided a DNN during the PDU session establishment, the UE shall stop timer T3396 if it is running for the DNN provided by the UE. If the UE did not provide a DNN during the PDU session establishment and the request type was different from "initial emergency request" and different from "existing emergency PDU session", the UE shall stop the timer T3396 associated with no DNN if it is running. If the PDU SESSION RELEASE COMMAND message was received for an emergency PDU session, the UE shall not stop the timer T3396 associated with no DNN if it is running. In an SNPN, the timer T3396 to be stopped includes:

1. the timer T3396 applied for all the equivalent SNPNs, associated with the RSNPN or an equivalent SNPN, and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and
2. the timer T3396 applied for the registered SNPN, associated with the RSNPN, and, if the UE supports access to an SNPN using credentials from a credentials holder, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.

If the PDU SESSION RELEASE COMMAND message is received without the Back-off timer value IE or includes 5GSM cause #39 "reactivation requested", and the UE provided an S-NSSAI and a DNN during the PDU session establishment, the UE shall stop timer T3584 if it is running for the [S-NSSAI of the PDU session, DNN] combination provided by the UE. If the UE did not provide an S-NSSAI during the PDU session establishment, the UE shall stop the timer T3584 associated with [no S-NSSAI, DNN] if it is running. If the UE did not provide a DNN during the PDU session establishment and the request type was different from "initial emergency request" and different from "existing emergency PDU session", the UE shall stop the timer T3584 associated with [S-NSSAI of the PDU session, no DNN] combination, if it is running. If the PDU SESSION RELEASE COMMAND message was received for an emergency PDU session, the UE shall not stop the timer T3584 associated with [S-NSSAI of the PDU session, no DNN] if it is running. If the UE provided neither a DNN nor an S-NSSAI during the PDU session establishment and the request type was different from "initial emergency request" and different from "existing emergency PDU session", the UE shall stop the timer T3584 associated with [no S-NSSAI, no DNN] if it is running. If the PDU SESSION RELEASE COMMAND message was received for an emergency PDU session, the UE shall not stop the timer T3584 associated with [no S-NSSAI, no DNN] if it is running. The timer T3584 to be stopped includes:

1. in a PLMN:
   1. the timer T3584 applied for all the PLMNs, if running; and
   2. the timer T3584 applied for the registered PLMN, if running; or
2. in an SNPN:
   1. the timer T3584 applied for all the equivalent SNPNs, and associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and
   2. the timer T3584 applied for the registered SNPN, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.

If the PDU SESSION RELEASE COMMAND message includes 5GSM cause #26 "insufficient resources" and the Back-off timer value IE, the UE shall ignore the 5GSM congestion re-attempt indicator IE provided by the network, if any, and the UE shall take different actions depending on the timer value received for timer T3396 in the Back-off timer value:

1. If the timer value indicates neither zero nor deactivated and a DNN was provided during the PDU session establishment, the UE shall stop timer T3396 associated with the corresponding DNN, if it is running. If the timer value indicates neither zero nor deactivated and no DNN was provided during the PDU session establishment and the request type was different from "initial emergency request" and different from "existing emergency PDU session", the UE shall stop timer T3396 associated with no DNN if it is running. In an SNPN, the timer T3396 to be stopped includes:
   1. the timer T3396 applied for all the equivalent SNPNs, and associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and
   2. the timer T3396 applied for the registered SNPN, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.
   The UE shall then start timer T3396 with the value provided in the Back-off timer value IE and:
   1. shall not send a PDU SESSION ESTABLISHMENT REQUEST message or PDU SESSION MODIFICATION REQUEST message with exception of those identified in subclause 6.4.2.1, for the same DNN that was sent by the UE, until timer T3396 expires or timer T3396 is stopped; and
   2. shall not send a PDU SESSION ESTABLISHMENT REQUEST message without an DNN and with request type different from "initial emergency request" and different from "existing emergency PDU session", or a PDU SESSION MODIFICATION REQUEST message with exception of those identified in subclause 6.4.2.1, for a non-emergency PDU session established without an DNN provided by the UE, if no DNN was provided during the PDU session establishment and the request type was different from "initial emergency request" and different from "existing emergency PDU session", until timer T3396 expires or timer T3396 is stopped.
   The UE shall not stop timer T3396 upon a PLMN change, SNPN change, or inter-system change;
2. if the timer value indicates that this timer is deactivated and a DNN was provided during the PDU session establishment, the UE shall stop timer T3396 associated with the corresponding DNN, if it is running. If the timer value indicates that this timer is deactivated and no DNN was provided during the PDU session establishment and the request type was different from "initial emergency request" and different from "existing emergency PDU session", the UE shall stop timer T3396 associated with no DNN if it is running. In an SNPN, the timer T3396 to be stopped includes:
   1. the timer T3396 applied for all the equivalent SNPNs, and associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and
   2. the timer T3396 applied for the registered SNPN, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.
   The UE:
   1. shall not send a PDU SESSION ESTABLISHMENT REQUEST message or PDU SESSION MODIFICATION REQUEST message with exception of those identified in subclause 6.4.2.1, for the same DNN until the UE is switched off, the USIM is removed, the entry in the "list of subscriber data" for the current SNPN is updated, or the UE receives a PDU SESSION MODIFICATION COMMAND message for the same DNN from the network, or a PDU SESSION AUTHENTICATION COMMAND message for the same DNN, or a PDU SESSION RELEASE COMMAND message without the Back-off timer value IE or including 5GSM cause #39 "reactivation requested" for the same DNN from the network; and
   2. shall not send a PDU SESSION ESTABLISHMENT REQUEST message without a DNN and with request type different from "initial emergency request" and different from "existing emergency PDU session", or a PDU SESSION MODIFICATION REQUEST message with exception of those identified in subclause 6.4.2.1, for a non-emergency PDU session established without a DNN provided by the UE, if no DNN was provided during the PDU session establishment and the request type was different from "initial emergency request" and different from "existing emergency PDU session", until the UE is switched off, the USIM is removed, the entry in the "list of subscriber data" for the current SNPN is updated, or the UE receives a PDU SESSION MODIFICATION COMMAND message for a non-emergency PDU session established without an DNN provided by the UE, or a PDU SESSION AUTHENTICATION COMMAND message for a non-emergency PDU session established without a DNN provided by the UE, or a PDU SESSION RELEASE COMMAND message without the Back-off timer value IE or including 5GSM cause #39 "reactivation requested" for a non-emergency PDU session established without a DNN provided by the UE.
   The timer T3396 remains deactivated upon a PLMN change, SNPN change, or inter-system change; and
3. if the timer value indicates zero, the UE:
   1. shall stop timer T3396 associated with the corresponding DNN, if running. In an SNPN, the timer T3396 to be stopped includes:
      1. the timer T3396 applied for all the equivalent SNPNs, and associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and
      2. the timer T3396 applied for the registered SNPN, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.
      The UE may send a PDU SESSION ESTABLISHMENT REQUEST message or PDU SESSION MODIFICATION REQUEST message for the same DNN; and
   2. if no DNN was provided during the PDU session establishment and the request type was different from "initial emergency request" and different from "existing emergency PDU session", the UE shall stop timer T3396 associated with no DNN, if running. In an SNPN, the timer T3396 to be stopped includes:
      1. the timer T3396 applied for all the equivalent SNPNs, and associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and
      2. the timer T3396 applied for the registered SNPN, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.
      The UE may send a PDU SESSION ESTABLISHMENT REQUEST message without a DNN, or a PDU SESSION MODIFICATION REQUEST message without an DNN provided by the UE.

In an SNPN, if the UE supports equivalent SNPNs, then the UE shall apply the timer T3396 for all the equivalent SNPNs. Otherwise, the UE shall apply the timer T3396 for the registered SNPN. If the PDU SESSION RELEASE COMMAND message includes 5GSM cause #26 "insufficient resources" and the Back-off timer value IE is not included, then the UE may send a PDU SESSION ESTABLISHMENT REQUEST message or PDU SESSION MODIFICATION REQUEST message for the same DNN or without a DNN. When the timer T3396 is running or the timer is deactivated, the UE is allowed to initiate a PDU session establishment procedure for emergency services. If the timer T3396 is running when the UE enters state 5GMM-DEREGISTERED, the UE remains switched on, and the USIM in the UE (if any) remains the same and the entry in the "list of subscriber data" for the SNPN to which timer T3396 is associated (if any) is not updated, then timer T3396 is kept running until it expires or it is stopped. If the UE is switched off when the timer T3396 is running, and if the USIM in the UE (if any) remains the same and the entry in the "list of subscriber data" for the SNPN to which timer T3396 is associated (if any) is not updated when the UE is switched on, the UE shall behave as follows:

• let t1 be the time remaining for T3396 timeout at switch off and let t be the time elapsed between switch off and switch on. If t1 is greater than t, then the timer shall be restarted with the value t1 – t. If t1 is equal to or less than t, then the timer need not be restarted. If the UE is not capable of determining t, then the UE shall restart the timer with the value t1.

If the 5GSM cause value is #39 "reactivation requested", the UE shall ignore the Back-off timer value IE provided by the network, if any. If the 5GSM cause value is #67 "insufficient resources for specific slice and DNN" and the Back-off timer value IE is included, the UE shall take different actions depending on the timer value received for timer T3584 in the Back-off timer value:

1. If the timer value indicates neither zero nor deactivated, and both an S-NSSAI and a DNN were provided by the UE during the PDU session establishment the UE shall stop timer T3584 associated with the [S-NSSAI of the PDU session, DNN] combination, if it is running. If the timer value indicates neither zero nor deactivated, an S-NSSAI and no DNN was provided during the PDU session establishment and the request type was different from "initial emergency request" and different from "existing emergency PDU session", the UE shall stop timer T3584 associated with [S-NSSAI of the PDU session, no DNN] combination, if it is running. If the timer value indicates neither zero nor deactivated, no S-NSSAI and a DNN was provided during the PDU session establishment, the UE shall stop timer T3584 associated with the [no S-NSSAI, DNN] combination, if it is running. If the timer value indicates neither zero nor deactivated and neither S-NSSAI nor DNN was provided during the PDU session establishment and the request type was different from "initial emergency request" and different from "existing emergency PDU session", the UE shall stop timer T3584 associated with the [no S-NSSAI, no DNN] combination, if it is running. The timer T3584 to be stopped includes:
   1. in a PLMN:
      1. the timer T3584 applied for all the PLMNs, if running; and
      2. the timer T3584 applied for the registered PLMN, if running; or
   2. in an SNPN:
      1. the timer T3584 applied for all the equivalent SNPNs, and associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and
      2. the timer T3584 applied for the registered SNPN, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.
   The UE shall then start timer T3584 with the value provided in the Back-off timer value IE.
   1. The UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message with request type different from "initial emergency request" and different from "existing emergency PDU session", or PDU SESSION MODIFICATION REQUEST message with the exception of those identified in subclause 6.4.2.1, for the [S-NSSAI of the PDU session, DNN] combination, until timer T3584 expires or timer T3584 is stopped;
   2. shall not send another PDU SESSION ESTABLISHMENT REQUEST message with request type different from "initial emergency request" and different from "existing emergency PDU session", or another PDU SESSION MODIFICATION REQUEST message with the exception of those identified in subclause 6.4.2.1, for the [S-NSSAI of the PDU session, no DNN] combination, if no DNN was provided during the PDU session establishment, until timer T3584 expires or timer T3584 is stopped;
   3. shall not send another PDU SESSION ESTABLISHMENT REQUEST message, or another PDU SESSION MODIFICATION REQUEST message with the exception of those identified in subclause 6.4.2.1, for the same [no S-NSSAI, DNN] combination, if no S-NSSAI was provided during the PDU session establishment, until timer T3584 expires or timer T3584 is stopped; and
   4. shall not send another PDU SESSION ESTABLISHMENT REQUEST message with request type different from "initial emergency request" and different from "existing emergency PDU session", or another PDU SESSION MODIFICATION REQUEST message with the exception of those identified in subclause 6.4.2.1, for the same [no S-NSSAI, no DNN] combination, if neither S-NSSAI nor DNN was provided during the PDU session establishment, until timer T3584 expires or timer T3584 is stopped.
   The UE shall not stop timer T3584 upon a PLMN change, SNPN change, or inter-system change;
2. if the timer value indicates that this timer is deactivated:
   1. if both S-NSSAI and DNN were provided by the UE during the PDU session establishment, the UE shall stop timer T3584 associated with the [S-NSSAI of the PDU session, DNN] combination, if running. The timer T3584 to be stopped includes:
      1. in a PLMN:
         1. the timer T3584 applied for all the PLMNs, if running; and
         2. the timer T3584 applied for the registered PLMN, if running; or
      2. in an SNPN:
         1. the timer T3584 applied for all the equivalent SNPNs, and associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and
         2. the timer T3584 applied for the registered SNPN, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.
      The UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message with request type different from "initial emergency request" and different from "existing emergency PDU session", or PDU SESSION MODIFICATION REQUEST message with exception of those identified in subclause 6.4.2.1, for the [S-NSSAI of the PDU session, DNN] combination that was sent by the UE, until the UE is switched off, the USIM is removed, the entry in the "list of subscriber data" for the current SNPN is updated, or the UE receives a PDU SESSION MODIFICATION COMMAND message for the [S-NSSAI of the PDU session, DNN] combination from the network, or a PDU SESSION AUTHENTICATION COMMAND message for the [S-NSSAI of the PDU session, DNN] combination from the network, or a PDU SESSION RELEASE COMMAND message without the Back-off timer value IE or including 5GSM cause #39 "reactivation requested" for the [S-NSSAI of the PDU session, DNN] combination from the network;
   2. if an S-NSSAI was provided but a DNN was not provided by the UE during the PDU session establishment, the UE shall stop timer T3584 associated with the [S-NSSAI of the PDU session, no DNN] combination, if running. The timer T3584 to be stopped includes:
      1. in a PLMN:
         1. the timer T3584 applied for all the PLMNs, if running; and
         2. the timer T3584 applied for the registered PLMN, if running; or
      2. in an SNPN:
         1. the timer T3584 applied for all the equivalent SNPNs, and associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and
         2. the timer T3584 applied for the registered SNPN, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.
      The UE shall not send a PDU SESSION ESTABLISHMENT REQUEST message with request type different from "initial emergency request" and different from "existing emergency PDU session", or a PDU SESSION MODIFICATION REQUEST message with exception of those identified in subclause 6.4.2.1, for the [S-NSSAI of the PDU session, no DNN] combination, if no DNN was provided during the PDU session establishment, until the UE is switched off, the USIM is removed, the entry in the "list of subscriber data" for the current SNPN is updated, or the UE receives an PDU SESSION MODIFICATION COMMAND message for a non-emergency PDU session established for the [S-NSSAI of the PDU session, no DNN] combination from the network, or a PDU SESSION AUTHENTICATION COMMAND message for a non-emergency PDU session established the [S-NSSAI of the PDU session, DNN] combination from the network, or a PDU SESSION RELEASE COMMAND message without the Back-off timer value IE or including 5GSM cause #39 "reactivation requested" for a non-emergency PDU session established for the [S-NSSAI of the PDU session, no DNN] combination from the network;
   3. if an S-NSSAI was not provided but a DNN was provided by the UE during the PDU session establishment, the UE shall stop timer T3584 associated with the [no S-NSSAI, DNN] combination, if running. The timer T3584 to be stopped includes:
      1. in a PLMN:
         1. the timer T3584 applied for all the PLMNs, if running; and
         2. the timer T3584 applied for the registered PLMN, if running; or
      2. in an SNPN:
         1. the timer T3584 applied for all the equivalent SNPNs, and associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and
         2. the timer T3584 applied for the registered SNPN, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.
      The UE shall not send a PDU SESSION ESTABLISHMENT REQUEST message, or a PDU SESSION MODIFICATION REQUEST message with exception of those identified in subclause 6.4.2.1, for the [no S-NSSAI, DNN], if no S-NSSAI was provided during the PDU session establishment, until the UE is switched off, the USIM is removed, the entry in the "list of subscriber data" for the current SNPN is updated, or the UE receives an PDU SESSION MODIFICATION COMMAND message for the [no S-NSSAI, DNN] combination from the network, or a PDU SESSION AUTHENTICATION COMMAND message for the [no S-NSSAI, DNN] combination from the network, or a PDU SESSION RELEASE COMMAND message without the Back-off timer value IE or including 5GSM cause #39 "reactivation requested" for the same [no S-NSSAI, DNN] combination from the network; and
   4. if neither S-NSSAI nor DNN were provided by the UE during the PDU session establishment, the UE shall stop timer T3584 associated with the [no S-NSSAI, no DNN] combination, if running. The timer T3584 to be stopped includes:
      1. in a PLMN:
         1. the timer T3584 applied for all the PLMNs, if running; and
         2. the timer T3584 applied for the registered PLMN, if running; or
      2. in an SNPN:
         1. the timer T3584 applied for all the equivalent SNPNs, and associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and
         2. the timer T3584 applied for the registered SNPN, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.
      The UE shall not send a PDU SESSION ESTABLISHMENT REQUEST message with request type different from "initial emergency request" and different from "existing emergency PDU session", or a PDU SESSION MODIFICATION REQUEST message with exception of those identified in subclause 6.4.2.1, for the [no S-NSSAI, no DNN] combination, if neither S-NSSAI nor DNN was provided during the PDU session establishment, until the UE is switched off, the USIM is removed, the entry in the "list of subscriber data" for the current SNPN is updated, or the UE receives an PDU SESSION MODIFICATION COMMAND message for a non-emergency PDU session established for the [no S-NSSAI, no DNN] combination from the network, or a PDU SESSION AUTHENTICATION COMMAND message for a non-emergency PDU session established for the [no S-NSSAI, no DNN] combination from the network or a PDU SESSION RELEASE COMMAND message without the Back-off timer value IE or including 5GSM cause #39 "reactivation requested" for a non-emergency PDU session established for the [no S-NSSAI, no DNN] combination from the network.
   The timer T3584 remains deactivated upon a PLMN change or inter-system change; and
3. if the timer value indicates zero:
   1. if both S-NSSAI and DNN were provided by the UE during the PDU session establishment, the UE shall stop timer T3584 associated with the [S-NSSAI of the PDU session, DNN] combination, if running. The timer T3584 to be stopped includes:
      1. in a PLMN:
         1. the timer T3584 applied for all the PLMNs, if running; and
         2. the timer T3584 applied for the registered PLMN, if running; or
      2. in an SNPN:
         1. the timer T3584 applied for all the equivalent SNPNs, and associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and
         2. the timer T3584 applied for the registered SNPN, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.
      The UE may send another PDU SESSION ESTABLISHMENT REQUEST message or PDU SESSION MODIFICATION REQUEST message for the [S-NSSAI of the PDU session, DNN] combination;
   2. if an S-NSSAI was provided but a DNN was not provided by the UE during the PDU session establishment, the UE shall stop timer T3584 associated with the [S-NSSAI of the PDU session, no DNN] combination, if running. The timer T3584 to be stopped includes:
      1. in a PLMN:
         1. the timer T3584 applied for all the PLMNs, if running; and
         2. the timer T3584 applied for the registered PLMN, if running; or
      2. in an SNPN:
         1. the timer T3584 applied for all the equivalent SNPNs, and associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and
         2. the timer T3584 applied for the registered SNPN, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.
      The UE may send another PDU SESSION ESTABLISHMENT REQUEST message or PDU SESSION MODIFICATION REQUEST message for the [S-NSSAI of the PDU session, no DNN] combination if the request type was different from "initial emergency request" and different from "existing emergency PDU session";
   3. if an S-NSSAI was not provided but a DNN was provided by the UE during the PDU session establishment, the UE shall stop timer T3584 associated with the [no S-NSSAI, DNN] combination, if running. The timer T3584 to be stopped includes:
      1. in a PLMN:
         1. the timer T3584 applied for all the PLMNs, if running; and
         2. the timer T3584 applied for the registered PLMN, if running; or
      2. in an SNPN:
         1. the timer T3584 applied for all the equivalent SNPNs, and associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and
         2. the timer T3584 applied for the registered SNPN, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.
      The UE may send another PDU SESSION ESTABLISHMENT REQUEST message, or PDU SESSION MODIFICATION REQUEST message for the [no S-NSSAI, DNN] combination; and
   4. if neither S-NSSAI nor DNN were provided by the UE during the PDU session establishment, the UE shall stop timer T3584 associated with the [no S-NSSAI, no DNN] combination, if running. The timer T3584 to be stopped includes:
      1. in a PLMN:
         1. the timer T3584 applied for all the PLMNs, if running; and
         2. the timer T3584 applied for the registered PLMN, if running; or
      2. in an SNPN:
         1. the timer T3584 applied for all the equivalent SNPNs, and associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and
         2. the timer T3584 applied for the registered SNPN, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.
      The UE may send another PDU SESSION ESTABLISHMENT REQUEST message, or PDU SESSION MODIFICATION REQUEST message for the [no S-NSSAI, no DNN] combination if the request type was different from "initial emergency request" and different from "existing emergency PDU session".

If the 5GSM congestion re-attempt indicator IE with the ABO bit set to "The back-off timer is applied in all PLMNs or all equivalent SNPNs" is included in the PDU SESSION RELEASE COMMAND message with the 5GSM cause value #67 "insufficient resources for specific slice and DNN", then the UE shall apply the timer T3584 for all the PLMNs or all the equivalent SNPNs. Otherwise, the UE shall apply the timer T3584 for the registered PLMN or the registered SNPN. If the 5GSM cause value is #67 "insufficient resources for specific slice and DNN" and the Back-off timer value IE is not included, then the UE may send another PDU SESSION ESTABLISHMENT REQUEST message or PDU SESSION MODIFICATION REQUEST message for the same [S-NSSAI, DNN] combination. When the timer T3584 is running or the timer is deactivated, the UE is allowed to initiate a PDU session establishment procedure for emergency services. If the timer T3584 is running when the UE enters state 5GMM-DEREGISTERED, the UE remains switched on, and the USIM in the UE (if any) remains the same and the entry in the "list of subscriber data" for the SNPN to which timer T3584 is associated (if any) is not updated, then timer T3584 is kept running until it expires or it is stopped. If the UE is switched off when the timer T3584 is running, and if the USIM in the UE (if any) remains the same and the entry in the "list of subscriber data" for the SNPN to which timer T3584 is associated (if any) is not updated when the UE is switched on, the UE shall behave as follows:

• let t1 be the time remaining for T3584 timeout at switch off and let t be the time elapsed between switch off and switch on. If t1 is greater than t, then the timer shall be restarted with the value t1 – t. If t1 is equal to or less than t, then the timer need not be restarted. If the UE is not capable of determining t, then the UE shall restart the timer with the value t1.

If the 5GSM cause value is #69 "insufficient resources for specific slice" and the Back-off timer value IE is included, the UE shall take different actions depending on the timer value received for timer T3585 in the Back-off timer value:

1. If the timer value indicates neither zero nor deactivated and an S-NSSAI was provided during the PDU session establishment, the UE shall stop timer T3585 associated with the S-NSSAI of the PDU session, if it is running. If the timer value indicates neither zero nor deactivated and no S-NSSAI was provided during the PDU session establishment and the request type was different from "initial emergency request" and different from "existing emergency PDU session", the UE shall stop timer T3585 associated with no S-NSSAI if it is running. The timer T3585 to be stopped includes:
   1. in a PLMN:
      1. the timer T3585 applied for all the PLMNs and for the access over which the PDU SESSION RELEASE COMMAND is received, if running;
      2. the timer T3585 applied for all the PLMNs and for both 3GPP access type and non-3GPP access type, if running;
      3. the timer T3585 applied for the registered PLMN and for the access over which the PDU SESSION RELEASE COMMAND is received, if running; and
      4. the timer T3585 applied for the registered PLMN and for both 3GPP access type and non-3GPP access type, if running; or
   2. in an SNPN:
      1. the timer T3585 applied for all the equivalent SNPNs and for the access over which the PDU SESSION AUTHENTICATION COMMAND message is received, associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running;
      2. the timer T3585 applied for all the equivalent SNPNs and for both 3GPP access type and non-3GPP access type, associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running;
      3. the timer T3585 applied for the registered SNPN and for the access over which the PDU SESSION AUTHENTICATION COMMAND message is received, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and
      4. the timer T3585 applied for the registered PLMN and for both 3GPP access type and non-3GPP access type, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.
   The UE shall then start timer T3585 with the value provided in the Back-off timer value IE and:
   1. if an S-NSSAI was provided by the UE during the PDU session establishment, the UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message, or PDU SESSION MODIFICATION REQUEST message with exception of those identified in subclause 6.4.2.1, for the S-NSSAI of the PDU session, until timer T3585 expires or timer T3585 is stopped; and
   2. if the request type was different from "initial emergency request" and from "existing emergency PDU session", and an S-NSSAI was not provided by the UE during the PDU session establishment, the UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message without an S-NSSAI and with request type different from "initial emergency request" and different from "existing emergency PDU session", or another PDU SESSION MODIFICATION REQUEST message with exception of those identified in subclause 6.4.2.1, for a non-emergency PDU session established without an S-NSSAI provided by the UE, until timer T3585 expires or timer T3585 is stopped.
   The UE shall not stop timer T3585 upon a PLMN change, SNPN change, or inter-system change;
2. if the timer value indicates that this timer is deactivated and an S-NSSAI was provided during the PDU session establishment, the UE shall stop timer T3585 associated with the S-NSSAI of the PDU session, if it is running. If the timer value indicates that this timer is deactivated and no S-NSSAI was provided during the PDU session establishment and the request type was different from "initial emergency request" and different from "existing emergency PDU session", the UE shall stop timer T3585 associated with no S-NSSAI if it is running. The timer T3585 to be stopped includes:
   1. in a PLMN:
      1. the timer T3585 applied for all the PLMNs and for the access over which the PDU SESSION RELEASE COMMAND is received, if running;
      2. the timer T3585 applied for all the PLMNs and for both 3GPP access type and non-3GPP access type, if running;
      3. the timer T3585 applied for the registered PLMN and for current access type or both 3GPP access type and non-3GPP access type, if running; and
      4. the timer T3585 applied for the registered PLMN and for both 3GPP access type and non-3GPP access type, if running; or
   2. in an SNPN:
      1. the timer T3585 applied for all the equivalent SNPNs and for the access over which the PDU SESSION AUTHENTICATION COMMAND message is received, associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running;
      2. the timer T3585 applied for all the equivalent SNPNs and for both 3GPP access type and non-3GPP access type, associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running;
      3. the timer T3585 applied for the registered SNPN and for the access over which the PDU SESSION AUTHENTICATION COMMAND message is received, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and
      4. the timer T3585 applied for the registered PLMN and for both 3GPP access type and non-3GPP access type, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.
   In addition:
   1. if an S-NSSAI was provided by the UE during the PDU session establishment, the UE shall not send another PDU SESSION ESTABLISHMENT REQUEST, or PDU SESSION MODIFICATION REQUEST with exception of those identified in subclause 6.4.2.1, for the S-NSSAI of the PDU session until the UE is switched off, the USIM is removed, the entry in the "list of subscriber data" for the current SNPN is updated, or a PDU SESSION MODIFICATION COMMAND message for the S-NSSAI of the PDU session from the network, or a PDU SESSION AUTHENTICATION COMMAND message for the S-NSSAI of the PDU session from the network, or a PDU SESSION RELEASE COMMAND message without the Back-off timer value IE or including 5GSM cause #39 "reactivation requested" for the S-NSSAI of the PDU session from the network; and
   2. if the request type was different from "initial emergency request" and from "existing emergency PDU session", and an S-NSSAI was not provided by the UE during the PDU session establishment, the UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message without an S-NSSAI and with request type different from "initial emergency request" and different from "existing emergency PDU session", or another PDU SESSION MODIFICATION REQUEST message with exception of those identified in subclause 6.4.2.1, for a non-emergency PDU session established without an S-NSSAI provided by the UE, until the UE is switched off, the USIM is removed, the entry in the "list of subscriber data" for the current SNPN is updated, or a PDU SESSION MODIFICATION COMMAND message for a non-emergency PDU session established without an S-NSSAI provided by the UE, or a PDU SESSION AUTHENTICATION COMMAND message for a non-emergency PDU session established without an S-NSSAI provided by the UE, or a PDU SESSION RELEASE COMMAND message without the Back-off timer value IE or including 5GSM cause #39 "reactivation requested" for a non-emergency PDU session established without an S-NSSAI provided by the UE.
   The timer T3585 remains deactivated upon a PLMN change, SNPN change, or inter-system change; and
3. if the timer value indicates zero:
   1. if an S-NSSAI was provided by the UE during the PDU session establishment, the UE shall stop timer T3585 associated with the S-NSSAI of the PDU session, if running. The timer T3585 to be stopped includes:
      1. in a PLMN:
         1. the timer T3585 applied for all the PLMNs and for the access over which the PDU SESSION RELEASE COMMAND is received, if running;
         2. the timer T3585 applied for all the PLMNs and for the access over which the PDU SESSION RELEASE COMMAND is received, if running;
         3. the timer T3585 applied for the registered PLMN and for current access type or both 3GPP access type and non-3GPP access type, if running; and
         4. the timer T3585 applied for the registered PLMN and for both 3GPP access type and non-3GPP access type, if running; or
      2. in an SNPN:
         1. the timer T3585 applied for all the equivalent SNPNs and for the access over which the PDU SESSION AUTHENTICATION COMMAND message is received, associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running;
         2. the timer T3585 applied for all the equivalent SNPNs and for both 3GPP access type and non-3GPP access type, associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running;
         3. the timer T3585 applied for the registered SNPN and for the access over which the PDU SESSION AUTHENTICATION COMMAND message is received, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and
         4. the timer T3585 applied for the registered PLMN and for both 3GPP access type and non-3GPP access type, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.
      The UE may send another PDU SESSION ESTABLISHMENT REQUEST, or PDU SESSION MODIFICATION REQUEST message for the S-NSSAI of the PDU session; and
   2. if no S-NSSAI was provided during the PDU session establishment and the request type was different from "initial emergency request" and different from "existing emergency PDU session", the UE shall stop timer T3585 associated with no S-NSSAI
      1. in a PLMN:
         1. the timer T3585 applied for all the PLMNs and for the access over which the PDU SESSION RELEASE COMMAND is received, if running,;
         2. the timer T3585 applied for all the PLMNs and for the access over which the PDU SESSION RELEASE COMMAND is received, if running;
         3. the timer T3585 applied for the registered PLMN and for current access type or both 3GPP access type and non-3GPP access type, if running; and
            D) the timer T3585 applied for the registered PLMN and for both 3GPP access type and non-3GPP access type, if running; or
      2. in an SNPN:
         1. the timer T3585 applied for all the equivalent SNPNs and for the access over which the PDU SESSION AUTHENTICATION COMMAND message is received, associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running;
         2. the timer T3585 applied for all the equivalent SNPNs and for both 3GPP access type and non-3GPP access type, associated with the RSNPN or an equivalent SNPN and with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running;
         3. the timer T3585 applied for the registered SNPN and for the access over which the PDU SESSION AUTHENTICATION COMMAND message is received, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running; and
         4. the timer T3585 applied for the registered PLMN and for both 3GPP access type and non-3GPP access type, associated with the RSNPN and, if the UE supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, if running.
      The UE may send another PDU SESSION ESTABLISHMENT REQUEST message without an S-NSSAI, or another PDU SESSION MODIFICATION REQUEST message without an S-NSSAI provided by the UE.

If the 5GSM congestion re-attempt indicator IE with the ABO bit set to "The back-off timer is applied in all PLMNs or all equivalent SNPNs" is included in the PDU SESSION RELEASE COMMAND message with the 5GSM cause value #69 "insufficient resources for specific slice", then the UE shall apply the timer T3585 for all the PLMNs or all the equivalent SNPNs. Otherwise, the UE shall apply the timer T3585 for the registered PLMN or the registered SNPN. If the 5GSM cause value is #69 "insufficient resources for specific slice" and the Back-off timer value IE is not included, then the UE may send another PDU SESSION ESTABLISHMENT REQUEST message or PDU SESSION MODIFICATION REQUEST message for the same S-NSSAI or without an S-NSSAI. When the timer T3585 is running or the timer is deactivated, the UE is allowed to initiate a PDU session establishment procedure for emergency services. If the timer T3585 is running when the UE enters state 5GMM-DEREGISTERED, the UE remains switched on, and the USIM in the UE (if any) remains the same and the entry in the "list of subscriber data" for the SNPN to which timer T3585 is associated (if any) is not updated, then timer T3585 is kept running until it expires or it is stopped. If the UE is switched off when the timer T3585 is running, and if the USIM in the UE (if any) remains the same and the entry in the "list of subscriber data" for the SNPN to which timer T3585 is associated (if any) is not updated when the UE is switched on, the UE shall behave as follows:

• let t1 be the time remaining for T3585 timeout at switch off and let t be the time elapsed between switch off and switch on. If t1 is greater than t, then the timer shall be restarted with the value t1 – t. If t1 is equal to or less than t, then the timer need not be restarted. If the UE is not capable of determining t, then the UE shall restart the timer with the value t1.

Upon PLMN change or SNPN change, if T3584 applied for the registered PLMN or the registered SNPN is running or is deactivated for an S-NSSAI, a DNN, and old PLMN or old SNPN, but T3584 is not running and is not deactivated for the S-NSSAI, the DNN, and new PLMN or new SNPN, then the UE is allowed to send a PDU SESSION ESTABLISHMENT REQUEST message for the same S-NSSAI and the same DNN in the new PLMN or new SNPN. Upon PLMN change or SNPN change, if T3585 applied for the registered PLMN or the registered SNPN is running or is deactivated for an S-NSSAI and old PLMN or old SNPN, but T3585 is not running and is not deactivated for the S-NSSAI and new PLMN or new SNPN, then the UE is allowed to send a PDU SESSION ESTABLISHMENT REQUEST message for the same S-NSSAI in the new PLMN or new SNPN. Upon SNPN change, if T3584 applied for all the equivalent SNPNs is running or is deactivated for an S-NSSAI, a DNN, and old SNPN, but T3584 is not running and is not deactivated for the S-NSSAI, the DNN, and new non-equivalent SNPN, then the UE is allowed to send a PDU SESSION ESTABLISHMENT REQUEST message for the same S-NSSAI and the same DNN in the new SNPN. Upon SNPN change, if T3585 applied for all the equivalent SNPNs is running or is deactivated for an S-NSSAI and old SNPN, but T3585 is not running and is not deactivated for the S-NSSAI and new non-equivalent SNPN, then the UE is allowed to send a PDU SESSION ESTABLISHMENT REQUEST message for the same S-NSSAI in the new SNPN. If the PDU SESSION RELEASE COMMAND message includes 5GSM cause #29 "user authentication or authorization failed" and the Back-off timer value IE, the UE shall behave as follows:

1. if the timer value indicates neither zero nor deactivated and:
   1. if the UE provided a DNN and S-NSSAI to the network during the PDU session establishment, the UE shall start the back-off timer with the value provided in the Back-off timer value IE for the PDU session establishment procedure and:
      1. in a PLMN, [PLMN, DNN, (mapped) HPLMN S-NSSAI] combination. The UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message for the same DNN and (mapped) HPLMN S-NSSAI in the current PLMN, until the back-off timer expires, the UE is switched off, or the USIM is removed; or
      2. in an SNPN, [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, DNN, (mapped) subscribed SNPN S-NSSAI] combination. The UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message for the same DNN and (mapped) subscribed SNPN S-NSSAI in the current SNPN using the selected entry of the "list of subscriber data" or selected PLMN subscription, until the back-off timer expires, the UE is switched off, the USIM is removed, or the selected entry of the "list of subscriber data" is updated;
   2. if the UE provided a DNN to the network during the PDU session establishment, the UE shall start the back-off timer with the value provided in the Back-off timer value IE for the PDU session establishment procedure and:
      1. in a PLMN, [PLMN, DNN] combination. The UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message for the same DNN in the current PLMN, until the back-off timer expires, the UE is switched off, or the USIM is removed; or
      2. in an SNPN, [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, DNN] combination. The UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message for the same DNN in the current PLMN using the selected entry of the "list of subscriber data" or selected PLMN subscription, until the back-off timer expires, the UE is switched off, the USIM is removed or the selected entry of the "list of subscriber data" is updated;
   3. if the UE did not provide a DNN or S-NSSAI or any of the two parameters to the network during the PDU session establishment, it shall start the back-off timer accordingly for the PDU session establishment procedure and:
      1. in a PLMN, the [PLMN, DNN, no S-NSSAI], [PLMN, no DNN, (mapped) HPLMN S-NSSAI] or [PLMN, no DNN, no S-NSSAI] combination. Dependent on the combination, the UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message for the same [PLMN, DNN, no S-NSSAI], [PLMN, no DNN, (mapped) HPLMN S-NSSAI] or [PLMN, no DNN, no S-NSSAI] combination in the current PLMN, until the back-off timer expires, the UE is switched off, or the USIM is removed; or
      2. in an SNPN, [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, DNN, no S-NSSAI], [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, no DNN, (mapped) subscribed SNPN S-NSSAI] or [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, no DNN, no S-NSSAI] combination. Dependent on the combination, the UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message for the same [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, DNN, no S-NSSAI], [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, no DNN, (mapped) subscribed SNPN S-NSSAI] or [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, no DNN, no S-NSSAI] combination in the current PLMN using the selected entry of the "list of subscriber data" or selected PLMN subscription, until the back-off timer expires, the UE is switched off, the USIM is removed or the selected entry of the "list of subscriber data" is updated; or
   4. if the UE did not provide a DNN to the network during the PDU session establishment, it shall start the back-off timer accordingly for the PDU session establishment procedure and:
      1. in a PLMN, the [PLMN, no DNN] combination. The UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message for the same [PLMN, no DNN] in the current PLMN, until the back-off timer expires, the UE is switched off, or the USIM is removed; or
      2. in an SNPN, [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, no DNN] combination. The UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message for the same [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, no DNN] in the current SNPN using the selected entry of the "list of subscriber data" or selected PLMN subscription, until the back-off timer expires, the UE is switched off, the USIM is removed, or the selected entry of the "list of subscriber data" is updated;
2. if the timer value indicates that this timer is deactivated and:
   1. if the UE provided a DNN and S-NSSAI to the network during the PDU session establishment, the UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message for:
      1. in a PLMN, the same DNN and (mapped) HPLMN S-NSSAI in the current PLMN, until the UE is switched off, or the USIM is removed; or
      2. in an SNPN, the same DNN and (mapped) subscribed SNPN S-NSSAI in the current SNPN using the selected entry of the "list of subscriber data" or selected PLMN subscription, until the UE is switched off, or the USIM is removed, or the selected entry of the "list of subscriber data" is updated;
   2. if the UE provided a DNN to the network during the PDU session establishment, the UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message for:
      1. in a PLMN, the same DNN in the current PLMN, until the UE is switched off, or the USIM is removed; or
      2. in an SNPN, the same DNN in the current SNPN using the selected entry of the "list of subscriber data" or selected PLMN subscription, until the UE is switched off, or the USIM is removed, or the selected entry of the "list of subscriber data" is updated;
   3. if the UE did not provide a DNN or S-NSSAI or any of the two parameters to the network during the PDU session establishment, the UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message for:
      1. in a PLMN, the same [PLMN, DNN, no S-NSSAI], [PLMN, no DNN, (mapped) HPLMN S-NSSAI] or [PLMN, no DNN, no S-NSSAI] combination in the current PLMN, until the UE is switched off, or the USIM is removed; or
      2. in an SNPN, the same [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, DNN, no S-NSSAI], [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, no DNN, (mapped) subscribed SNPN S-NSSAI] or [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, no DNN, no S-NSSAI] combination in the current SNPN using the selected entry of the "list of subscriber data" or selected PLMN subscription, until the UE is switched off, or the USIM is removed, or the selected entry of the "list of subscriber data" is updated; or
   4. if the UE did not provide a DNN to the network during the PDU session establishment, the UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message for:
      1. in a PLMN, the same [PLMN, no DNN] in the current PLMN, until the UE is switched off, or the USIM is removed; or
      2. in an SNPN, the same [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, no DNN] combination in the current SNPN using the selected entry of the "list of subscriber data" or selected PLMN subscription, until the UE is switched off, or the USIM is removed, or the selected entry of the "list of subscriber data" is updated; and
3. if the timer value indicates zero, the UE may send another PDU SESSION ESTABLISHMENT REQUEST message:
   1. in a PLMN, for the same combination of [PLMN, DNN, (mapped) HPLMN S-NSSAI], [PLMN, DNN, no S-NSSAI], [PLMN, no DNN, (mapped) HPLMN S-NSSAI], or [PLMN, no DNN, no S-NSSAI] in the current PLMN; or
   2. in an SNPN, for the same combination of [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, DNN, (mapped) subscribed SNPN S-NSSAI], [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, DNN, no S-NSSAI], [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, no DNN, (mapped) subscribed SNPN S-NSSAI], or [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, no DNN, no S-NSSAI] in the current SNPN.

The UE shall not stop any back-off timer:

1. upon a PLMN or SNPN change;
2. upon an inter-system change; or
3. upon registration over another access type.

If the PDU SESSION RELEASE COMMAND message includes:

1. 5GSM cause #29 "user authentication or authorization failed"; and
2. the service-level-AA response in the Service-level-AA container IE with the SLAR field set to the value of "Service level authentication and authorization was not successful or service level authorization is revoked",

the UE shall forward the service-level-AA response to the upper layers, so the UUAA authorization data is deleted as specified in TS 33.256. The UE shall transport the PDU SESSION RELEASE COMPLETE message and the PDU session ID, using the NAS transport procedure as specified in subclause 5.4.5. Upon receipt of a PDU SESSION RELEASE COMPLETE message, the SMF shall stop timer T3592 and shall consider the PDU session as released.

If the PDU SESSION RELEASE COMMAND message was sent along the N1 SM delivery skip allowed indication towards AMF, then upon receipt of an indication that N1 SM delivery was skipped, the SMF shall stop timer T3592 and shall consider the PDU session as released.

The following abnormal cases can be identified:

1. Expiry of timer T3592.
   The SMF shall, on the first expiry of the timer T3592, retransmit the PDU SESSION RELEASE COMMAND message and shall reset and start timer T3592. This retransmission is repeated four times, i.e. on the fifth expiry of timer T3592, the SMF shall abort the procedure.
2. Collision of network-requested PDU session release procedure and UE-requested PDU session modification procedure.
   When the SMF receives a PDU SESSION MODIFICATION REQUEST message during the network-requested PDU session release procedure, and the PDU session indicated in PDU SESSION MODIFICATION REQUEST message is the PDU session that the SMF had requested to release, the SMF shall ignore the PDU SESSION MODIFICATION REQUEST message and proceed with the PDU session release procedure.
3. Collision of network-requested PDU session release procedure and UE-requested PDU session release procedure.
   If the SMF receives a PDU SESSION RELEASE REQUEST message after sending a PDU SESSION RELEASE COMMAND message with the PTI IE set to "No procedure transaction identity assigned" to the UE, and the PDU session ID in the PDU SESSION RELEASE REQUEST message is the same as the PDU session ID in the PDU SESSION RELEASE COMMAND message:
   • if the Access type IE is included in the PDU SESSION RELEASE COMMAND message and the PDU session is an MA PDU session and having user-plane resources established on the access different from the access indicated in the Access type IE in the PDU SESSION RELEASE COMMAND message, the SMF shall proceed both the UE-requested PDU session release procedure and network-requested PDU session release procedure;
   • otherwise, the SMF shall ignore the PDU SESSION RELEASE REQUEST message and proceed with the network-requested PDU session release procedure.
4. Collision of re-establishment of the user-plane resources and network-requested PDU session release procedure for the same PDU session.
   If the SMF receives an indication from the AMF to re-establish the user-plane resources during the network-requested PDU session release procedure for the same PDU session, the SMF shall not re-establish the user-plane resources for the PDU session as specified in subclause 5.2.2.3.2.2 of TS 29.502 and proceed with the network-requested PDU session release procedure.

The following abnormal cases can be identified:

1. PDU session inactive for the received PDU session ID.
   If the PDU session ID in the PDU SESSION RELEASE COMMAND message belongs to any PDU session in state PDU SESSION INACTIVE in the UE, the UE shall include the 5GSM cause #43 "Invalid PDU session identity" in the 5GSM STATUS message, and set the PDU session ID to the received PDU session ID in the UL NAS TRANSPORT message as specified in subclause 5.4.5.
2. User-plane resources of the MA PDU session on the access indicated in the Access type IE not established.
   If the PDU session is an MA PDU session and has user-plane resources established on a single access different from the access indicated in the Access type IE, the UE shall not diagnose an error, further process the release command and consider the user-plane resources of the MA PDU session on the access indicated in the Access type IE as successfully released.