3GPP 23.501 v20.2.0 — the document's own text
5.48.1 Overview
Taught in 27. Overload, energy, deployment and the rest (The 5G system architecture, in depth).
The "subscription-based routing to a target core network" feature forwards traffic related with a UE to a target (partner) PLMN as specified in clauses 4.2.3 and 4.2.4.
This subscription-based routing to a target core network feature may apply to all signalling and User Plane traffic related to a UE or only to the SM signalling and User Plane traffic related to the PDU sessions established by the UE to some DNN(s) and/or S-NSSAI(s) and/or related to a SUPI range and/or subscription data.
NOTE: This function assumes relevant SLA between the HPLMN of the UE and the target PLMN.
The NF/NF Service discovery and selection mechanisms for serving the UE (all signalling and User Plane traffic) or a PDU session (corresponding SM signalling and User Plane traffic) in the target PLMN makes use of a corresponding Routing Indicator, or SUPI range, or S-NSSAI(s) and DNN(s) as defined in clauses 6.3.1 and 6.3.8 to discover and select a NF/NF Service in the target network.