5.16.4.9 Handling of PDU Sessions for Emergency Services

The QoS Flows of a PDU Session associated with the emergency DNN shall be dedicated for IMS emergency sessions and shall not allow any other type of traffic. The emergency contexts shall not be changed to non-emergency contexts and vice versa. The UPF shall block any traffic that is not from or to addresses of network functions (e.g. P-CSCF) providing Emergency Services.

If there is already an emergency PDU Session over a given Access Type (3GPP access or non-3GPP access), the UE shall not request another emergency PDU Session over any Access Type except for handing over the existing emergency PDU Session to the other Access Type.

If the SMF receives a new emergency PDU session establishment request and an emergency PDU Session exists for the same UE over any Access Type, the SMF shall remove the existing SM context locally and clear the associated resources in the network and proceed with the new request.

NOTE: If the UE releases emergency PDU session locally and requests for establishment of a new one before the SMF has released the emergency PDU session due to PDU session inactivity as specified in clause 4.3.4.2 of TS 23.502 [3], the above duplicate emergency PDU session handling in the network removes the old emergency PDU session as part of establishing a new one. This releases all resources related with the old emergency PDU Session.

The ARP reserved for emergency service shall only be assigned to QoS Flows associated with an emergency PDU Session. If the UE is Emergency Registered over a given access, it shall not request a PDU Session to any other DNN over this access.