3GPP 23.501 v20.2.0 — the document's own text

5.16.4.6 QoS for Emergency Services

Taught in 21. Emergency calls, messages, voice and location (The 5G system architecture, in depth).

Local regulation may require supporting emergency calls from an unauthorised UE. In such a case, the SMF may not have subscription data. Additionally, the local network may want to provide Emergency Services support differently than what is allowed by a UE subscription. Therefore, the initial QoS parameters used for establishing Emergency Services are configured in the V-SMF (local network) in the SMF Emergency Configuration Data.

This functionality is used by the UE Requested PDU Session Establishment procedure when establishing Emergency Services.