When the UE is not operating in SNPN access operation mode, if PLMN selection specified in TS 23.122 is applicable (e.g., at switch-on, recovery from lack of 3GPP coverage, or user selection of applicable 3GPP access technology), the PLMN selection to select the highest priority PLMN according to these specifications is performed before any access network discovery. When the UE is operating in SNPN access operation mode over non-3gpp access, if SNPN selection specified in TS 23.122 is applicable (e.g., at switch-on, recovery from lack of 3GPP coverage, or user selection of applicable 3GPP access technology), the SNPN selection to select a highest priority SNPN according to these specifications is performed before any access network discovery. In the access network discovery procedure, the UE can get ANDSP information on available access networks in its vicinity and can use this information when determining the presence of operator preferred access networks. Determination of the presence of access networks requires using radio access specific procedures, which are not further described here.

The UE may obtain WLAN Selection Policy (WLANSP) rules information by pre-configuration or by downloading the policy information from the PCF as specified in TS 23.503. The policy contains the UE access network discovery and selection related policy information to help the UE in discovering and selecting a WLAN access network (see TS 24.526). The UE may receive multiple valid WLANSP rules from PLMNs to be used when not operating in SNPN access operation mode. When the UE is in the home PLMN, the UE uses the valid WLANSP rules from the home PLMN to select an available WLAN. When the UE is roaming and the UE has valid rules from several of the home PLMN, a visited PLMN and a PLMN equivalent to the visited PLMN, the UE uses the WLANSP rules in the following order of decreasing priority:

1. the valid WLANSP rules from the visited PLMN;
2. the valid WLANSP rules from the equivalent PLMN in which the UE last received WLANSP; and
3. the valid WLANSP rules from the home PLMN.

The UE may be provisioned with multiple valid WLANSP rules to be used when operating in SNPN access operation mode over non-3gpp access:

1. pre-configured from the subscribed SNPN or CH with AAA server and stored in the selected entry of the "list of subscriber data", if selected or HPLMN (associated with the PLMN subscription, if selected);
2. received from the PCF of the subscribed SNPN associated with the selected entry of the "list of subscriber data" if selected) or HPLMN (associated with the PLMN subscription, if selected); or
3. received from the PCF of a non-subscribed SNPN.

If the UE is in the subscribed SNPN, the UE uses the valid WLANSP rules from the subscribed SNPN. If the UE is in a non-subscribed SNPN and has valid WLANSP rules both from:

1. the subscribed SNPN, the CH with AAA server or the HPLMN; and
2. the non-subscribed SNPN;

the UE uses the WLANSP rules in the following order of decreasing priority:

1. the valid WLANSP rules from the non-subscribed SNPN; and
2. the valid WLANSP rules from the subscribed SNPN, the CH with AAA server or the HPLMN.

A WLANSP rule is valid if it meets the validity conditions included in the WLANSP rule (if provided). The UE may apply the techniques specific to the WLAN access technologies to discover available WLAN access networks. Such techniques will not be further described here. In addition, the UE may obtain information on operator preferred WLAN access networks via ANDSP.

In this release of the specification, only selection of WLAN access network is supported. The ANDSP policy contains WLANSP rules for the UE to select a WLAN access network. Rules for selecting other types of non-3GPP access networks are not specified.

When the UE is not operating in SNPN access operation mode, there are two modes of PLMN selection, namely, manual PLMN selection and automatic PLMN selection. The UE follows one of the following two procedures defined in clause 5.3.2.2 and clause 5.3.2.3 depending on its implementation. The N5CW device that is not registered or cannot register via NG-RAN performs manual mode WLAN selection procedure as defined in clause 5.3.2.2. The PLMN selected in accordance with these procedures determines the WLAN that is selected. When the selected WLAN is a trusted non-3GPP IP access and the UE decides to access 5GC via trusted non-3GPP IP access, the UE shall derive a NAI from the identity of the selected PLMN and use the NAI as the identity for authentication and authorization with the PLMN and usage of the WLAN. The procedures described in this clause 5.3A shall apply to the UE and the N5CW device.

The UE not operating in SNPN access operation mode shall determine which PLMNs are available from each WLAN on the list of available WLANs constructed using the WLAN selection procedure described in clause 5.3.2 using the following procedures:

1. the UE selects a WLAN from the list of selected WLAN(s) constructed using the WLAN selection procedure described in clause 5.3.2;
2. if both the WLAN selected in step i) and the UE support ANQP specified in IEEE Std 802.11 [19] and if the UE did not obtain a list of realms using ANQP in clause 5.3.2.3 item 1, the UE shall send an ANQP request for a list of realms (i.e. ANQP-elements "NAI Realm"), PLMN identities (i.e. ANQP-element "3GPP Cellular Network"), or both; and
3. if either the WLAN selected in step i) or the UE does not support ANQP (see IEEE Std 802.11 [19]) or the UE does not receive a list of realms in item ii), an EAP-Request/Identity is received and the EAP-Request/Identity does not include one or more of realms, PLMN identities, or both (encoded in accordance with RFC 4284), the UE supports IEEE 802.1x authentication (see IEEE Std 802.1X™ [30]), the UE shall request a list of realms, PLMN identities, or both interworking with that WLAN by sending the EAP-Response/Identity message including as identity the alternative NAI; and
4. the UE repeats this procedure for all WLANs from the available list of WLANs as constructed using the WLAN selection procedure described in clause 5.3.2.
   The UE shall convert any received PLMN identities into realms of the PLMNs using the rules defined in clause 19 and clause 28 of TS 23.003. The N5CW device shall convert any received PLMN identities into realms of the PLMNs using the rules defined in clause 28 of TS 23.003.

The UE not operating in SNPN access operation mode indicates to the user the PLMNs which are available via the WLAN. The UE may obtain the PLMNs available for WLAN access using procedures as described in clause 5.3A.2. The UE selects the PLMN based on the user preference.