For a 5G ProSe enabled UE as specified in TS 23.304, if the UE does not have access to emergency service via any of the IP-CANs in Table E.1, the UE (in the role of 5G ProSe Remote UE) may attempt to obtain emergency service via 5G ProSe UE-to-Network Relay if available. Refer to TS 23.304 for further details how the 5G ProSe Remote UE initiates emergency service via the 5G ProSe UE-to-Network Relay.

A 5G ProSe Remote UE identifies that the dialled digits correspond to an emergency call as specified in TS 22.101. For 5G ProSe Layer-3 UE-to-Network relaying, the 5G ProSe Remote UE may obtain P-CSCF address from the 5G ProSe UE-to-Network Relay via DHCP. The 5G ProSe Remote UE sets the access type "3GPP-NR-ProSe-L2UNR" or "3GPP-NR-ProSe-L3UNR" to P-CSCF for the access via 5G ProSe UE-to-Network Relay depending on whether Layer-2 or Layer-3 relaying is applied.

When a 5G ProSe Remote UE performs an emergency registration or initiates an emergency session over a 5G ProSe UE-to-Network Relay, if the operator policy requires network provided location using PCC-based solutions for the UE location, the P-CSCF may retrieve location information from the access network as defined in TS 23.503 and include it in the emergency session request as described in TS 23.228. When a 5G ProSe Remote UE establishes an emergency call over a 5G ProSe UE-to-Network Relay, the 5G ProSe Remote UE shall include in the IMS emergency request the NR Cell Global Identity (NCGI) obtained from the 5G ProSe UE-to-Network Relay e.g. during the 5G ProSe UE-to-Network Relay Discovery procedure specified in TS 23.304. When the P-CSCF determines that the emergency call is from a 5G ProSe Remote UE based on the access type "3GPP-NR-ProSe-L3UNR", the P-CSCF provides to the E-CSCF the NCGI and the UE Identity of 5G ProSe UE-to-Network Relay received from the PCF. The E-CSCF uses the NCGI and UE Identity of 5G ProSe UE-to-Network Relay to query the LRF to validate the NCGI provided by the 5G ProSe Remote UE as described in clause 4.3.1.