Section: 4.22.3.4 Home-routed, the UE registered to different PLMNs over both access
Content: In the case of home-routed roaming, when the UE is registered to different PLMNs over 3GPP access and non-3GPP access, the procedure for establishing a MA PDU Session when the UE requests a single-access PDU Session in an ATSSS capable PLMN but no policy in the UE and no local restrictions mandate a single access, is the same with the procedure specified in clause 4.22.2.2.2, with the following clarifications and modifications: - In step 1, the UE sets Request Type to initial request and it may include an "MA PDU Network-Upgrade Allowed" indication in UL NAS Transport message and its ATSSS Capabilities as defined in clause 5.32.2 of TS 23.501[ System architecture for the 5G System (5GS) ]  [2] in PDU Session Establishment Request message. - In step 2, if the AMF receives the "MA PDU Network-Upgrade Allowed" indication, the AMF may select a V-SMF that supports MA PDU sessions. - In step 3, the AMF sends the "MA PDU Network-Upgrade Allowed" indication, if received from the UE. - In step 6, the V-SMF provides the "MA PDU Network-Upgrade Allowed" indication, if received from AMF. - After step 6, if the H-SMF receives the "MA PDU Network-Upgrade Allowed" indication, the H-SMF may decide to convert the single-access PDU Session requested by the UE into a MA PDU Session, if dynamic PCC is not to be used. The H-SMF may take this decision based on local operator policy, subscription data indicating whether the MA PDU session is allowed or not and/or other conditions, which are not specified in the present document. - In step 9, if dynamic PCC is to be used for the MA PDU Session, the H-SMF sends an "MA PDU Network-Upgrade Allowed" indication to H-PCF in the SM Policy Control Create message if the MA PDU session is allowed based on the subscription data. The H-SMF also provides the ATSSS Capabilities of the MA PDU session. - In step 13, the H-SMF sends "MA PDU session Accepted" indication to V-SMF in the Nsmf_PDUSession_Create Response message. - In step 14, the V-SMF includes the "MA PDU session Accepted" indication in the Namf_Communication_N1N2MessageTransfer message to the AMF. The AMF mark this PDU session as MA PDU session based on the received "MA PDU session Accepted" indication. - In step 16, the UE receives a PDU Session Establishment Accept message, which includes ATSSS rules and indicates to UE that the requested single-access PDU session was established as a MA PDU Session. - After the MA PDU Session is established over one access, the UE shall send another PDU Session Establishment Request over the other access containing the same PDU Session ID that was provided over the first access. The UE also sets Request Type as "MA PDU Request" in UL NAS Transport message.