5.5.1.2.6 Initial registration for emergency services not accepted by the network

Upon receiving the REGISTRATION REJECT message including 5GMM cause #5 "PEI not accepted", the UE shall enter the state 5GMM-DEREGISTERED.NO-SUPI. If the REGISTRATION REJECT message is received,

• over 3GPP access; or
• over non-3GPP access and is integrity protected;

and the UE also supports the registration procedure over the other access, the UE shall in addition handle 5GMM parameters and 5GMM state for this access, as described for this 5GMM cause value.

Upon receiving the REGISTRATION REJECT message including 5GMM cause value which is not #5 "PEI not accepted", the UE shall perform the actions as described in clause 5.5.1.2.5 with the following addition: the UE shall inform the upper layers of the failure of the procedure.

NOTE 1: This can result in the upper layers requesting implementation specific mechanisms, e.g. procedures specified in 3GPP TS 24.229 [14] can result in the emergency call being attempted to another IP-CAN.

If the initial registration request for emergency services fails due to abnormal cases, the UE shall perform the actions as described in clause 5.5.1.2.7 and inform the upper layers of the failure to access the network or the failure of the procedure.

NOTE 2: This can result in the upper layers requesting other implementation specific mechanisms, e.g. procedures specified in 3GPP TS 24.229 [14] can result in the emergency call being attempted to another IP-CAN.

In a shared network, upon receiving the REGISTRATION REJECT message, the UE shall perform the actions as described in clause 5.5.1.2.5, and shall:

• inform the upper layers of the failure of the procedure; or

NOTE 3: The upper layers can request implementation specific mechanisms, e.g. procedures specified in 3GPP TS 24.229 [14] that can result in the emergency call being attempted to another IP-CAN.

• attempt to perform a PLMN or SNPN selection in the shared network and, if an initial registration for emergency services was not already attempted with the selected PLMN or SNPN and the REGISTRATION REQUEST message, for which the REGISTRATION REJECT message was received, is:
• not for sending a PDU SESSION ESTABLISHMENT REQUEST message with request type set to "existing emergency PDU session", initiate an initial registration for emergency services with the selected PLMN or SNPN; or
• for sending a PDU SESSION ESTABLISHMENT REQUEST message with request type set to "existing emergency PDU session", and:
• the selected PLMN is an equivalent PLMN or the selected SNPN is an equivalent SNPN, initiate an initial registration for emergency services with the selected PLMN or SNPN; and
• the selected PLMN is not an equivalent PLMN or the selected SNPN is not an equivalent SNPN, perform a PLMN or SNPN selection and initiate an initial registration for emergency services with the selected PLMN or SNPN if an initial registration for emergency services was not already attempted with the selected PLMN or SNPN.

In a shared network, if the initial registration request for emergency services fails due to abnormal cases, the UE shall perform the actions as described in clause 5.5.1.2.7 and shall:

• inform the upper layers of the failure of the procedure; or

NOTE 4: The upper layers can request implementation specific mechanisms, e.g. procedures specified in 3GPP TS 24.229 [14] that can result in the emergency call being attempted to another IP-CAN.

• attempt to perform a PLMN or SNPN selection in the shared network and, if an initial registration for emergency services was not already attempted with the selected PLMN or SNPN and the REGISTRATION REQUEST message is:
• not for sending a PDU SESSION ESTABLISHMENT REQUEST message with request type set to "existing emergency PDU session", initiate an initial registration for emergency services with the selected PLMN or SNPN; or
• for sending a PDU SESSION ESTABLISHMENT REQUEST message with request type set to "existing emergency PDU session", and:
• the selected PLMN is an equivalent PLMN or the selected SNPN is an equivalent SNPN, initiate an initial registration for emergency services with the selected PLMN or SNPN; and
• the selected PLMN is not an equivalent PLMN or the selected SNPN is not an equivalent SNPN, perform a PLMN or SNPN selection and initiate an initial registration for emergency services with the selected PLMN or SNPN if an initial registration for emergency services was not already attempted with the selected PLMN or SNPN.