5.18.3 Network selection by the UE

NOTE 1: This clause applies to UEs not operating in SNPN access mode. Network selection for UEs set to operate in SNPN access mode is described in clause 5.30.2.4.

A UE that has a subscription to one of the sharing core network operators shall be able to select this core network operator while within the coverage area of the shared network and to receive subscribed services from that core network operator.

Each cell in shared NG-RAN shall in the broadcast system information include the PLMN IDs concerning available core network operators in the shared network.

When a UE performs an Initial Registration to a network, one of available PLMNs shall be selected to serve the UE. UE uses all the received broadcast PLMN IDs in its PLMN (re)selection processes which is specified in TS 23.122 [17]. UE shall inform the NG-RAN of the selected PLMN so that the NG-RAN can route correctly. The NG-RAN shall inform the core network of the selected PLMN.

NOTE 2: For Indirect Network Sharing as specified in clause 5.18.1, the broadcast PLMN IDs include the PLMN IDs representing participating operators and a UE from a participating operator selects a PLMN ID representing the participating operator as specified in TS 23.122 [17].

NOTE 3: The serving AMF of hosting operator's network acquires the relevant UE subscription data from the participating operator's network during the Registration procedure as described in clause 4.2.2.2.2 of TS 23.502 [3].

In the case of Indirect Network Sharing, in this Release of the specifications, if hosting operator's network identifies that a UE is not from a participating operator when the UE selects a PLMN ID representing the participating operator, then the hosting operator network rejects the UE with an existing cause value during the registration procedure.

As per any network, after Initial Registration to the shared network and while remaining served by the shared network, the network selection procedures specified in TS 23.122 [17] may cause the UE to perform a reselection of another available PLMN.

UE uses all of the received broadcast PLMN IDs in its cell and PLMN (re)selection processes.