6.4.1.4.3 Handling of network rejection not due to congestion control

If the 5GSM cause value is different from #26 "insufficient resources", #28 "unknown PDU session type", #39 "reactivation requested", #46 "out of LADN service area", #50 "PDU session type IPv4 only allowed", #51 "PDU session type IPv6 only allowed", #54 "PDU session does not exist", #57 "PDU session type IPv4v6 only allowed", #58 "PDU session type Unstructured only allowed", #61 "PDU session type Ethernet only allowed", #67 "insufficient resources for specific slice and DNN", #68 "not supported SSC mode", #69 "insufficient resources for specific slice", #86 "UAS services not allowed", and #33 "requested service option not subscribed" upon sending PDU SESSION ESTABLISHMENT REQUEST to establish an MA PDU session, and the Back-off timer value IE is included, the UE shall behave as follows: (if the UE is a UE configured for high priority access in selected PLMN or SNPN, exceptions are specified in clause 6.2.12):

• if the timer value indicates neither zero nor deactivated and:
• if the UE provided a DNN and S-NSSAI to the network during the PDU session establishment and the 5GSM cause value is different from #27 "missing or unknown DNN", 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:
• 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
• in an SNPN, [SNPN, 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;
• if the UE provided a DNN to the network during the PDU session establishment and the 5GSM cause value is #27 "missing or unknown DNN", 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:
• 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
• in an SNPN, [SNPN, 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 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;
• 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 and the 5GSM cause value is different from #27 "missing or unknown DNN", it shall start the back-off timer accordingly for the PDU session establishment procedure and:
• in a PLMN, [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
• in an SNPN, [SNPN, selected entry of the "list of subscriber data" or selected PLMN subscription, DNN, no S-NSSAI], [SNPN, selected entry of the "list of subscriber data" or selected PLMN subscription, no DNN, (mapped) subscribed SNPN S-NSSAI] or [SNPN, 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, selected entry of the "list of subscriber data" or selected PLMN subscription, DNN, no S-NSSAI], [SNPN, selected entry of the "list of subscriber data" or selected PLMN subscription, no DNN, (mapped) subscribed SNPN S-NSSAI] or [SNPN, 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
• if the UE did not provide a DNN to the network during the PDU session establishment and the 5GSM cause value is #27 "missing or unknown DNN", it shall start the back-off timer accordingly for the PDU session establishment procedure and:
• in a PLMN, [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
• in an SNPN, [SNPN, 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, selected entry of the "list of subscriber data" or selected PLMN subscription, no 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;
• if the timer value indicates that this timer is deactivated and:
• if the UE provided a DNN and S-NSSAI to the network during the PDU session establishment and the 5GSM cause value is different from #27 "missing or unknown DNN", the UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message for:
• 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
• 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, the USIM is removed, or the selected entry of the "list of subscriber data" is updated;
• if the UE provided a DNN to the network during the PDU session establishment and the 5GSM cause value is #27 "missing or unknown DNN", the UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message for:
• in a PLMN, the same DNN in the current PLMN, until the UE is switched off, or the USIM is removed; or
• 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, the USIM is removed, or the selected entry of the "list of subscriber data" is updated;
• 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 and the 5GSM cause value is different from #27 "missing or unknown DNN", the UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message for:
• 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
• 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, the USIM is removed, or the selected entry of the "list of subscriber data" is updated; or
• if the UE did not provide a DNN to the network during the PDU session establishment and the 5GSM cause value is #27 "missing or unknown DNN", the UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message for:
• in a PLMN, the same [PLMN, no DNN] in the current PLMN, until the UE is switched off, or the USIM is removed; or
• in an SNPN, 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 UE is switched off, the USIM is removed, or the selected entry of the "list of subscriber data" is updated; and
• if the timer value indicates zero and the 5GSM cause value is different from #27 "missing or unknown DNN", the UE may send another PDU SESSION ESTABLISHMENT REQUEST message for:
• in a PLMN, 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. If the timer value indicates zero and the 5GSM cause value is #27 "missing or unknown DNN", the UE may send another PDU SESSION ESTABLISHMENT REQUEST message for the same combination of [PLMN, DNN], or [PLMN, no DNN] in the current PLMN; or
• in an SNPN, 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 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 using the selected entry of the "list of subscriber data" or selected PLMN subscription. If the timer value indicates zero and the 5GSM cause value is #27 "missing or unknown DNN", the UE may send another PDU SESSION ESTABLISHMENT REQUEST message for the same combination of [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, DNN], or [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.

If the Back-off timer value IE is not included, then the UE shall ignore the Re-attempt indicator IE provided by the network in the PDU SESSION ESTABLISHMENT REJECT message, if any.

• Additionally, if the 5GSM cause value is #8 "operator determined barring", #32 "service option not supported", #33 "requested service option not subscribed" upon sending PDU SESSION ESTABLISHMENT REQUEST not to establish an MA PDU session, or #70 "missing or unknown DNN in a slice", then:
• the UE not operating in SNPN access operation mode shall proceed as follows:
• if the UE is registered in the HPLMN or in a PLMN that is within the EHPLMN list, the UE shall behave as described above in the present clause using the configured SM Retry Timer value as specified in 3GPP TS 24.368 [17] or in USIM file NASCONFIG as specified in 3GPP TS 31.102 [22], if available, as back-off timer value; and

NOTE 1: The way to choose one of the configured SM Retry Timer values for back-off timer value is up to UE implementation if the UE is configured with:- an SM Retry Timer value in ME as specified in 3GPP TS 24.368 [17]; and- an SM Retry Timer value in USIM file NASCONFIG as specified in 3GPP TS 31.102 [22].

• otherwise, if the UE is not registered in its HPLMN or in a PLMN that is within the EHPLMN list, or if the SM Retry Timer value is not configured, the UE shall behave as described above in the present clause, using the default value of 12 minutes for the back-off timer; or
• the UE operating in SNPN access operation mode shall proceed as follows:
• if:

A) the SM Retry Timer value for the current SNPN as specified in 3GPP TS 24.368 [17] is available; or

B) the UE used the USIM for registration to the current SNPN and the SM Retry Timer value in USIM file NASCONFIG as specified in 3GPP TS 31.102 [22] is available;

then the UE shall behave as described above in the present clause using the configured SM Retry Timer value as back-off timer value; or

NOTE 2: The way to choose one of the configured SM Retry Timer values for back-off timer value is up to UE implementation if both conditions in bullets A) and B) above are satisfied.

• otherwise, the UE shall behave as described above in the present clause, using the default value of 12 minutes for the back-off timer.
• For 5GSM cause value #27 "missing or unknown DNN", then:
• the UE not operating in SNPN access operation mode shall proceed as follows:
• if the UE is registered in the HPLMN or in a PLMN that is within the EHPLMN list, the UE shall start the back-off timer with the configured SM Retry Timer value as specified in 3GPP TS 24.368 [17] or in USIM file NASCONFIG as specified in 3GPP TS 31.102 [22], if available, as back-off timer value for the PDU session establishment procedure and the [PLMN, DNN] or [PLMN, no 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; and

NOTE 3: The way to choose one of the configured SM Retry Timer values for back-off timer value is up to UE implementation if the UE is configured with:- an SM Retry Timer value in ME as specified in 3GPP TS 24.368 [17]; and- an SM Retry Timer value in USIM file NASCONFIG as specified in 3GPP TS 31.102 [22].

• otherwise, if the UE is not registered in its HPLMN or in a PLMN that is within the EHPLMN list, or if the SM Retry Timer value is not configured, the UE shall start the back-off timer with the default value of 12 minutes as back-off timer value for the PDU session establishment procedure and the [PLMN, DNN] or [PLMN, no 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
• the UE operating in SNPN access operation mode shall proceed as follows:
• if:

A) the SM Retry Timer value for the current SNPN as specified in 3GPP TS 24.368 [17] is available; or

B) the UE used the USIM for registration to the current SNPN and the SM Retry Timer value in USIM file NASCONFIG as specified in 3GPP TS 31.102 [22] is available;

then:

the UE shall start the back-off timer with the configured SM Retry Timer value as back-off timer value for the PDU session establishment procedure and the [SNPN, selected entry of the "list of subscriber data" or selected PLMN subscription, DNN] or [SNPN, 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 DNN in the current SNPN using the selected entry in the "list of subscriber data" or selected PLMN subscription, until the back-off timer expires, the UE is switched off, the UICC containing the USIM is removed or the selected entry of the "list of subscriber data" is updated; or

NOTE 4: The way to choose one of the configured SM Retry Timer values for back-off timer value is up to UE implementation if both conditions in bullets A) and B) above are satisfied.

• otherwise:
• the UE shall start the back-off timer with the default value of 12 min as back-off timer value for the PDU session establishment procedure and the [SNPN, selected entry of the "list of subscriber data" or selected PLMN subscription, DNN] or [SNPN, selected entry in 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 DNN in the current SNPN using the selected entry of the "list of subscriber data", until the back-off timer expires, the UE is switched off, the UICC containing the USIM is removed or the selected entry of the "list of subscriber data" is updated; and
• For 5GSM cause values different from #8 "operator determined barring", #27 "missing or unknown DNN", #32 "service option not supported", #33 "requested service option not subscribed" and #70 "missing or unknown DNN in a slice", the UE behaviour regarding the start of a back-off timer is specified in clause 6.2.12.

The UE shall not stop any back-off timer:

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

If the network indicates that a back-off timer for the PDU session establishment procedure is deactivated, then it remains deactivated;

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

NOTE 5: This means the back-off timer can still be running or be deactivated for the given 5GSM procedure when the UE returns to the PLMN or SNPN or when it performs inter-system change back from S1 mode to N1 mode. Thus, the UE can still be prevented from sending another PDU SESSION ESTABLISHMENT REQUEST message for the combination of [PLMN, DNN, (mapped) HPLMN S-NSSAI], [PLMN, DNN, no S-NSSAI], [PLMN, no DNN, (mapped) HPLMN S-NSSAI], [PLMN, no DNN, no S-NSSAI], [PLMN, DNN], or [PLMN, no DNN] in the PLMN, or for the combination of [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, DNN, (mapped) subscribed 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 S-NSSAI], [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, no DNN, no S-NSSAI], [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, DNN], or [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, no DNN] in the SNPN.

If the back-off timer is started upon receipt of a PDU SESSION ESTABLISHMENT REJECT (i.e. the timer value was provided by the network, a configured value is available or the default value is used as explained above) or the back-off timer is deactivated, the UE behaves as follows:

• after a PLMN or SNPN change:
• the UE may send a PDU SESSION ESTABLISHMENT REQUEST message for:
• in a PLMN, the combination of [new PLMN, DNN, (mapped) HPLMN S-NSSAI], [new PLMN, DNN, no S-NSSAI], [new PLMN, no DNN, (mapped) HPLMN S-NSSAI], or [new PLMN, no DNN, no S-NSSAI] in the new PLMN, if the back-off timer is not running and is not deactivated for the PDU session establishment procedure and the combination of [new PLMN, DNN, (mapped) HPLMN S-NSSAI], [new PLMN, DNN, no S-NSSAI], [new PLMN, no DNN, (mapped) HPLMN S-NSSAI], or [new PLMN, no DNN, no S-NSSAI]; or
• in an SNPN, the combination of [new SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, DNN, (mapped) subscribed SNPN S-NSSAI], [new SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, DNN, no S-NSSAI], [new PLMN, the selected entry of the "list of subscriber data" or selected PLMN subscription, no DNN, (mapped) subscribed SNPN S-NSSAI], or [new SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, no DNN, no S-NSSAI] in the new SNPN, if the back-off timer is not running and is not deactivated for the PDU session establishment procedure and the combination of [new SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, DNN, (mapped) subscribed SNPN S-NSSAI], [new SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, DNN, no S-NSSAI], [new SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, no DNN, (mapped) subscribed SNPN S-NSSAI], or [new SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, no DNN, no S-NSSAI];
• as an implementation option, for the 5GSM cause value #8 "operator determined barring", #32 "service option not supported", #33 "requested service option not subscribed" and #70 "missing or unknown DNN in a slice", if the network does not include a Re-attempt indicator IE, the UE may decide not to automatically send another PDU SESSION ESTABLISHMENT REQUEST message for:
• in a PLMN, 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] using the same PDU session type if the UE is registered to a new PLMN which is in the list of equivalent PLMNs; or
• in an SNPN, if the UE supports equivalent SNPNs, 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] using the same PDU session type and using the selected entry of the "list of subscriber data" or selected PLMN subscription, if the UE is registered to a new SNPN which is in the list of equivalent SNPNs; and
• as an implementation option, for the 5GSM cause value #27 "missing or unknown DNN", if the network does not include a Re-attempt indicator IE, the UE may decide not to automatically send another PDU SESSION ESTABLISHMENT REQUEST message for:
• in a PLMN, the same combination of [PLMN, DNN] or [PLMN, no DNN] using the same PDU session type if the UE is registered to a new PLMN which is in the list of equivalent PLMNs; or
• in an SNPN, if the UE supports equivalent SNPNs, the same combination of [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, DNN] or [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, no DNN] using the same PDU session type if the UE is registered to a new SNPN which is in the list of equivalent SNPNs; or
• if the network does not include the Re-attempt indicator IE to indicate whether re-attempt in S1 mode is allowed, or the UE ignores the Re-attempt indicator IE, e.g. because the Back-off timer value IE is not included, then:
• if the UE is registered in its HPLMN or in a PLMN that is within the EHPLMN list and the back-off timer is running for the combination of [PLMN, DNN, (mapped) HPLMN S-NSSAI] or [PLMN, DNN, no S-NSSAI], the UE shall apply the configured SM_RetryAtRATChange value as specified in 3GPP TS 24.368 [17] or in USIM file NASCONFIG as specified in 3GPP TS 31.102 [22], if available, to determine whether the UE may attempt a PDN connectivity procedure for the same [PLMN, DNN] combination in S1 mode. If the back-off timer is running for the combination of [PLMN, no DNN, (mapped) HPLMN S-NSSAI] or [PLMN, no DNN, no S-NSSAI], the same applies for the PDN connectivity procedure for the [PLMN, no DNN] combination in S1 mode accordingly; and

NOTE 6: The way to choose one of the configured SM_RetryAtRATChange values for back-off timer value is up to UE implementation if the UE is configured with:- an SM_RetryAtRATChange value in ME as specified in 3GPP TS 24.368 [17]; and- an SM_RetryAtRATChange value in USIM file NASCONFIG as specified in 3GPP TS 31.102 [22].

• if the UE is not registered in its HPLMN or in a PLMN that is within the EHPLMN list, or if the NAS configuration MO as specified in 3GPP TS 24.368 [17] is not available and the value for inter-system change is not configured in the USIM file NASCONFIG, then the UE behaviour regarding a PDN connectivity procedure for the same [PLMN, DNN] or [PLMN, no DNN] combination in S1 mode is unspecified; and
• if the network includes the Re-attempt indicator IE indicating that re-attempt in an equivalent PLMN or SNPN is not allowed, then depending on the timer value received in the Back-off timer value IE, for:
• in a PLMN, each combination of a PLMN from the equivalent PLMN list and the respective [DNN, (mapped) HPLMN S-NSSAI], [DNN, no S-NSSAI], [no DNN, (mapped) HPLMN S-NSSAI], or [no DNN, no S-NSSAI] combination, the UE shall start a back-off timer for the PDU session establishment procedure with the value provided by the network, or deactivate the respective back-off timer as follows:
• if the Re-attempt indicator IE additionally indicates that re-attempt in S1 mode is allowed, the UE shall start or deactivate the back-off timer for N1 mode only; and
• otherwise, the UE shall start or deactivate the back-off timer for S1 and N1 mode; or
• in a SNPN, if the UE supports equivalent SNPNs, each combination of a SNPN from the equivalent SNPN list and the respective [the selected entry of the "list of subscriber data" or selected PLMN subscription, DNN, (mapped) subscribed SNPN S-NSSAI], [the selected entry of the "list of subscriber data" or selected PLMN subscription, DNN, no S-NSSAI], [the selected entry of the "list of subscriber data" or selected PLMN subscription, no DNN, (mapped) subscribed SNPN S-NSSAI], or [the selected entry of the "list of subscriber data" or selected PLMN subscription, no DNN, no S-NSSAI] combination, the UE shall start a back-off timer for the PDU session establishment procedure with the value provided by the network, or deactivate the respective back-off timer, for N1 mode.

If the back-off timer for a [PLMN, DNN] or [PLMN, no DNN] combination, was started or deactivated in S1 mode upon receipt of PDN CONNECTIVITY REJECT message (see 3GPP TS 24.301 [15]) and the network indicated that re-attempt in N1 mode is allowed, then this back-off timer does not prevent the UE from sending a PDU SESSION ESTABLISHMENT REQUEST message in this PLMN for the same DNN, or without DNN, after inter-system change to N1 mode. If the network indicated that re-attempt in N1 mode is not allowed, the UE shall not send any PDU SESSION ESTABLISHMENT REQUEST message in this PLMN for the same DNN in combination with any S-NSSAI or without S-NSSAI, or in this PLMN without DNN in combination with any S-NSSAI or without S-NSSAI, after inter-system change to N1 mode until the timer expires, the UE is switched off or the USIM is removed.

NOTE 7: The back-off timer is used to describe a logical model of the required UE behaviour. This model does not imply any specific implementation, e.g. as a timer or timestamp.

NOTE 8: Reference to back-off timer in this section can either refer to use of timer T3396 or to use of a different packet system specific timer within the UE. Whether the UE uses T3396 as a back-off timer or it uses different packet system specific timers as back-off timers is left up to UE implementation.

When the back-off timer is running or the timer is deactivated, the UE is allowed to initiate a PDU session establishment procedure if the procedure is for emergency services.

If the 5GSM cause value is #28 "unknown PDU session type" and the PDU SESSION ESTABLISHMENT REQUEST message contained a PDU session type IE indicating a PDU session type, the UE shall ignore the Back-off timer value IE and Re-attempt indicator IE provided by the network, if any. The UE may send another PDU SESSION ESTABLISHMENT REQUEST message to establish a new PDU session with the PDU session type IE indicating another PDU session type, e.g. using another value which can be used for the rejected component in another route selection descriptor, if any, as specified in 3GPP TS 24.526 [19]. The behaviour of the UE for 5GSM cause value #28 also applies if the PDU session is a MA PDU Session.

If the 5GSM cause value is #39 "reactivation requested", the UE shall ignore the Back-off timer value IE and Re-attempt indicator IE provided by the network, if any.

NOTE 9: Further UE behaviour upon receipt of 5GSM cause value #39 is up to the UE implementation.

If the 5GSM cause value is #46 "out of LADN service area", the UE shall ignore the Back-off timer value IE and Re-attempt indicator IE provided by the network, if any. If the UE is not located inside the LADN service area, the UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message or another PDU SESSION MODIFICATION REQUEST message except for indicating a change of 3GPP PS data off UE status for the LADN DNN provided by the UE during the PDU session establishment procedure until the LADN information for the specific LADN DNN or the extended LADN information for the specific LADN DNN and S-NSSAI is updated as described in clause 5.4.4 and clause 5.5.1. If the UE is not located inside the LADN service area, the UE shall not indicate the PDU session(s) for the LADN DNN provided by the UE during the PDU session establishment procedure in the Uplink data status IE included in the SERVICE REQUEST message until the LADN information for the specific LADN DNN or the extended LADN information for the specific LADN DNN and S-NSSAI is updated as described in clause 5.4.4 and clause 5.5.1.

NOTE 10: Based on UE implementation, the UE locating inside the LADN service area can send another PDU SESSION ESTABLISHMENT REQUEST message or PDU SESSION MODIFICATION REQUEST message for the LADN DNN which was rejected with the 5GSM cause value #46 "out of LADN service area".

NOTE 10A: If the UE does not receive a CONFIGURATION UPDATE COMMAND message with new LADN information within an implementation dependent time, the UE can request this information by initiating a registration procedure for mobility or periodic registration update (see clause 5.5.1.3.2, item q).

If the 5GSM cause value is #50 "PDU session type IPv4 only allowed", #51 "PDU session type IPv6 only allowed", #57 "PDU session type IPv4v6 only allowed", #58 "PDU session type Unstructured only allowed", or #61 "PDU session type Ethernet only allowed", the UE shall ignore the Back-off timer value IE provided by the network, if any. The UE shall evaluate the URSP rules if available as specified in 3GPP TS 24.526 [19]. The UE shall not subsequently send another PDU SESSION ESTABLISHMENT REQUEST message for:

• in a PLMN, the same DNN (or no DNN, if no DNN was indicated by the UE) and the same (mapped) HPLMN S-NSSAI (or no S-NSSAI, if no S-NSSAI was indicated by the UE) to obtain a PDU session type different from the one allowed by the network until any of the following conditions is fulfilled:
• the UE is registered to a new PLMN which was not in the list of equivalent PLMNs at the time when the PDU SESSION ESTABLISHMENT REJECT message was received;
• the UE is registered to a new PLMN which was in the list of equivalent PLMNs at the time when the PDU SESSION ESTABLISHMENT REJECT message was received, and either the network did not include a Re-attempt indicator IE in the PDU SESSION ESTABLISHMENT REJECT message or the Re-attempt indicator IE included in the message indicated that re-attempt in an equivalent PLMN is allowed;
• the UE is switched off; or
• the USIM is removed; or
• in an SNPN, the same DNN (or no DNN, if no DNN was indicated by the UE) and the same (mapped) subscribed SNPN S-NSSAI (or no S-NSSAI, if no S-NSSAI was indicated by the UE), using the selected entry of the "list of subscriber data" or selected PLMN subscription until any of the following conditions is fulfilled:
• the UE is registered to a new SNPN which was not in the list of equivalent SNPNs at the time when the PDU SESSION ESTABLISHMENT REJECT message was received;
• the UE is registered to a new SNPN which was in the list of equivalent SNPNs at the time when the PDU SESSION ESTABLISHMENT REJECT message was received, and either the network did not include a Re-attempt indicator IE in the PDU SESSION ESTABLISHMENT REJECT message or the Re-attempt indicator IE included in the message indicated that re-attempt in an equivalent SNPN is allowed;
• the UE is switched off;
• the USIM is removed; or
• the selected entry of the "list of subscriber data" is updated.

For the 5GSM cause values #50 "PDU session type IPv4 only allowed", #51 "PDU session type IPv6 only allowed", #57 "PDU session type IPv4v6 only allowed", #58 "PDU session type Unstructured only allowed", and #61 "PDU session type Ethernet only allowed", the UE shall ignore the value of the RATC bit in the Re-attempt indicator IE provided by the network, if any.

NOTE 11: For the 5GSM cause values #50 "PDU session type IPv4 only allowed", #51 "PDU session type IPv6 only allowed", #57 "PDU session type IPv4v6 only allowed", #58 "PDU session type Unstructured only allowed", and #61 "PDU session type Ethernet only allowed", re-attempt in S1 mode for the same DNN (or no DNN, if no DNN was indicated by the UE) is only allowed using the PDU session type(s) indicated by the network.

If the 5GSM cause value is #54 "PDU session does not exist", the UE shall ignore the Back-off timer value IE and Re-attempt indicator IE provided by the network, if any. If the PDU session establishment procedure is to perform handover of an existing PDU session between 3GPP access and non-3GPP access, the UE shall release locally the existing PDU session with the PDU session ID included in the PDU SESSION ESTABLISHMENT REJECT message. The UE may initiate another UE-requested PDU session establishment procedure with the request type set to "initial request" in the subsequent PDU SESSION ESTABLISHMENT REQUEST message to establish a PDU session with:

• in a PLMN, the same DNN (or no DNN, if no DNN was indicated by the UE) and the same (mapped) HPLMN S-NSSAI (or no S-NSSAI, if no S-NSSAI was indicated by the UE); or
• in an SNPN, the same DNN (or no DNN, if no DNN was indicated by the UE) and the same (mapped) subscribed SNPN S-NSSAI (or no S-NSSAI, if no S-NSSAI was indicated by the UE) using the selected entry of the "list of subscriber data" or selected PLMN subscription.

NOTE 12: User interaction is necessary in some cases when the UE cannot re-establish the PDU session(s) automatically.

If the 5GSM cause value is #68 "not supported SSC mode", the UE shall ignore the Back-off timer value IE and Re-attempt indicator IE provided by the network, if any. The UE shall evaluate the URSP rules if available as specified in 3GPP TS 24.526 [19]. The UE shall not subsequently send another PDU SESSION ESTABLISHMENT REQUEST message for:

• in a PLMN, the same DNN (or no DNN, if no DNN was indicated by the UE) and the same (mapped) HPLMN S-NSSAI (or no S-NSSAI, if no S-NSSAI was indicated by the UE) using the same SSC mode or an SSC mode which was not included in the Allowed SSC mode IE until any of the following conditions is fulfilled:
• the UE is registered to a new PLMN which was not in the list of equivalent PLMNs at the time when the PDU SESSION ESTABLISHMENT REJECT message was received;
• the SSC mode which is used to access to the DNN (or no DNN, if no DNN was indicated by the UE) and the (mapped) HPLMN S-NSSAI (or no S-NSSAI, if no S-NSSAI was indicated by the UE) is changed by the UE which subsequently requests a new SSC mode in the Allowed SSC mode IE or no SSC mode;
• the UE is switched off; or
• the USIM is removed; or
• in an SNPN, the same DNN (or no DNN, if no DNN was indicated by the UE) and the same subscribed SNPN S-NSSAI (or no S-NSSAI, if no S-NSSAI was indicated by the UE) using the same SSC mode or an SSC mode which was not included in the Allowed SSC mode IE, using the selected entry of the "list of subscriber data" or selected PLMN subscription until any of the following conditions is fulfilled:
• the UE is registered to a new SNPN which was not in the list of equivalent SNPNs at the time when the PDU SESSION ESTABLISHMENT REJECT message was received;
• the SSC mode which is used to access to the DNN (or no DNN, if no DNN was indicated by the UE) and the (mapped) subscribed SNPN S-NSSAI (or no S-NSSAI, if no S-NSSAI was indicated by the UE) is changed by the UE which subsequently requests a new SSC mode in the Allowed SSC mode IE or no SSC mode;
• the UE is switched off;
• the USIM is removed, or
• the selected entry of the "list of subscriber data" is updated.

If the UE receives the 5GSM cause value is #33 "requested service option not subscribed" upon sending PDU SESSION ESTABLISHMENT REQUEST to establish an MA PDU session, the UE shall ignore the Back-off timer value IE and Re-attempt indicator IE provided by the network, if any. The UE shall evaluate URSP rules, if available, as specified in 3GPP TS 24.526 [19] and the UE may send PDU SESSION ESTABLISHMENT REQUEST after evaluating those URSP rules.

If the 5GSM cause value is #86 "UAS services not allowed", the UE shall ignore the Back-off timer value IE and Re-attempt indicator IE provided by the network, if any, and shall behave as specified in clause 6.4.1.4.1.

Upon receipt of an indication from 5GMM sublayer that the 5GSM message was not forwarded because the DNN is not supported or not subscribed in a slice along with a PDU SESSION ESTABLISHMENT REQUEST message with the PDU session ID IE set to the PDU session ID of the PDU session, the UE shall stop timer T3580, shall abort the procedure and shall behave as follows:

• if the timer value indicates neither zero nor deactivated, the UE shall start the back-off timer with the value received from the 5GMM sublayer for the PDU session establishment procedure and:
• in a PLMN, the [PLMN, DNN, S-NSSAI] combination or the [PLMN, DNN, no S-NSSAI] combination, if no S-NSSAI was provided during the PDU session establishment. The UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message in the PLMN for the same DNN and the same S-NSSAI that were sent by the UE, or for the same DNN and no S-NSSAI if S-NSSAI that was not sent by the UE, until:
• the back-off timer expires;
• the UE is switched off;

iii) the USIM is removed; or

• the DNN is included in the LADN information or extended LADN information and the network provides the LADN information or extended LADN information during the registration procedure or the generic UE configuration update procedure; or
• in an SNPN, the [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, DNN, S-NSSAI] combination or the [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, DNN, no S-NSSAI] combination, if no S-NSSAI was provided during the PDU session establishment. The UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message in the SNPN for the same DNN and the same S-NSSAI that were sent by the UE, or for the same DNN and no S-NSSAI if S-NSSAI that was not sent by the UE, 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;

iii) the USIM is removed;

• the selected entry of the "list of subscriber data" is updated; or
• the DNN is included in the LADN information or extended LADN information and the network provides the LADN information or extended LADN information during the registration procedure or the generic UE configuration update procedure;
• if the timer value is not received from the 5GMM sublayer or the timer value indicates that this timer is deactivated, the UE shall not send another PDU SESSION ESTABLISHMENT REQUEST message:
• in the PLMN for the same DNN and the same S-NSSAI that were sent by the UE, or for the same DNN and no S-NSSAI if S-NSSAI that was not sent by the UE, until:
• the UE is switched off;
• the USIM is removed; or

iii) the DNN is included in the LADN information or extended LADN information and the network provides the LADN information or extended LADN information during the registration procedure or the generic UE configuration update procedure; and

• in the SNPN, for the same DNN and the same S-NSSAI that were sent by the UE, or for the same DNN and no S-NSSAI if S-NSSAI that was not sent by the UE, using the selected entry of the "list of subscriber data" or selected PLMN subscription, until:
• the UE is switched off;
• the USIM is removed;

iii) the selected entry of the "list of subscriber data" is updated; or

iii) the DNN is included in the LADN information or extended LADN information and the network provides the LADN information or extended LADN information during the registration procedure or the generic UE configuration update procedure; and

• if the timer value indicates zero, the UE may send another PDU SESSION ESTABLISHMENT REQUEST message:
• in a PLMN, for the same combination of [PLMN, DNN, S-NSSAI], [PLMN, DNN, no S-NSSAI] in the current PLMN; or
• in an SNPN, for the same combination of [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, DNN, S-NSSAI], [SNPN, the selected entry of the "list of subscriber data" or selected PLMN subscription, DNN, no S-NSSAI] in the current SNPN.