Section: 5.5.1.2.6A Initial registration for initiating an emergency PDU session not accepted by the network
Content: If the network cannot accept an initial registration request with 5GS registration type IE set to "initial registration" and for sending a PDU SESSION ESTABLISHMENT REQUEST message with request type set to "initial emergency request", the UE shall perform the procedures as described in subclause 5.5.1.2.5. Then if the UE is in the same selected PLMN or SNPN where the last initial registration request was attempted, the UE shall: a) inform the upper layers of the failure of the procedure; or NOTE 1: This can result in the upper layers requesting implementation specific mechanisms, e.g. procedures specified in 3GPP TS 24.229[ IP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3 ]  [14] can result in the emergency call being attempted to another IP-CAN. b) attempt initial registration for emergency services. If the network cannot accept an initial registration request with 5GS registration type IE set to "initial registration", for establishing an emergency PDU session and the PDU session needs to be established due to handover of an existing PDN connection for emergency bearer services, the UE shall perform the procedures as described in subclause 5.5.1.2.5. Then if the UE is in the same selected PLMN or equivalent PLMN or the same selected SNPN or equivalent SNPN, where the last initial registration request was attempted, the UE shall attempt initial registration for emergency services. If the initial registration request, with 5GS registration type IE set to "initial registration" and for initiating an emergency PDU session, fails due to abnormal case b) in subclause 5.5.1.2.7, the UE shall perform the actions as described in subclause 5.5.1.2.7 and inform the upper layers of the failure to access the network. NOTE 2: This can result in the upper layers requesting implementation specific mechanisms, e.g. procedures specified in 3GPP TS 24.229[ IP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3 ]  [14] can result in the emergency call being attempted to another IP-CAN. If the initial registration request, with 5GS registration type IE set to "initial registration" and for initiating an emergency PDU session, fails due to abnormal cases c), d) or e) in subclause 5.5.1.2.7, the UE shall perform the actions as described in subclause 5.5.1.2.7. Then if the UE is in: a) the same selected PLMN or SNPN where the last initial registration request was attempted and the PDU session does not need to be established due to handover of an existing PDN connection for emergency bearer services, the UE shall: - inform the upper layers of the failure of the procedure; or NOTE 3: This can result in the upper layers requesting implementation specific mechanisms, e.g. procedures specified in 3GPP TS 24.229[ IP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3 ]  [14] can result in the emergency call being attempted to another IP-CAN. - attempt initial registration for emergency services; or b) the same selected PLMN or equivalent PLMN or the same selected SNPN or equivalent SNPN, where the last initial registration request was attempted and the PDU session needs to be established due to handover of an existing PDN connection for emergency bearer services, attempt initial registration for emergency services.