Abstract: A User Equipment (UE) including a wireless transceiver and a controller is provided. The controller obtains information indicating that the UE is not allowed to access a 3GPP core network over which one or both or none of the 3GPP access network and the non-3GPP access network. Also, the controller refrains the UE from accessing the 3GPP core network over the indicated one or both of the 3GPP access network and the non-3GPP access network in response to the information indicating that the UE is not allowed to access the 3GPP core network over one or both of the 3GPP access network and the non-3GPP access network.

Abstract: Solutions pertaining to adjusted public land mobile network (PLMN) search in mobile initiated connection only (MICO) mode in mobile communications are proposed. An apparatus implemented in a UE activates a MICO mode. The apparatus then postpones a periodic PLMN search in response to the UE being in the MICO mode, with the periodic PLMN search being controlled by a timer.

Abstract: A method of registering to slices with mapped S-NSSAI alone in a 5GS is described. The method can include, upon a UE entering a VPLMN, the UE having a first PDN connection or a first PDU session that is to be transferred to the VPLMN and associated with a first HPLMN S-NSSAI, determining whether the UE has a first VPLMN S-NSSAI applicable in the VPLMN corresponding to the first HPLMN S-NSSAI. If not, a registration request message can be transmitted to the VPLMN. The registration request message can include the first HPLMN S-NSSAI as a first mapped S-NSSAI for indicating a slice of the VPLMN to which the UE intends to register.

Abstract: Examples pertaining to improvement to signaling over satellite access in mobile communications are described. A user equipment (UE) initiates a procedure with a cell of a network over a satellite access. In response, the UE receives a message from the network indicating that the procedure cannot be completed due to an aspect of the satellite access. Then, the UE reattempts to complete the procedure responsive to a condition being met.

Abstract: Methods and apparatus are provided for EPS fallback status report by the modem to the upper layers. In one embodiment, the mobile terminal (MT) initiates a 5G voice call, detects an EPSFB triggered by the wireless network, identifies one or more EPSFB status and sends one or more EPSFB status indicators to at least one upper layer based on the identified one or more EPSFB status. In one embodiment, the EPS fall back is a redirection procedure. In another embodiment, the EPS fallback is a handover procedure. In yet another embodiment, the one or more EPSFB status indictors comprising a redirection to EPS started indicator, a handover to EPS started indicator, a redirection to EPS failed indicator, a handover to EPS failed indicator, a redirection to EPS success indicator, and a handover to EPS success indicator. In one embodiment, the MT sends EPSFB status indicators using AT command.

Abstract: Examples pertaining to user equipment (UE) handling of forbidden tracking area identifier (TAI) list information elements (IEs) in an Evolved Packet System (EPS) SERVICE ACCEPT message in mobile communications are described. A user equipment (UE) transmits a CONTROL PLANE SERVICE REQUEST message to an EPS network node of a wireless network. In response, the UE receives a SERVICE ACCEPT message from the EPS network node. The SERVICE ACCEPT message includes either or both of the following: (i) one or more forbidden tracking area identifiers (TAIs) for a list of “forbidden tracking areas for roaming” information element (IE); and (ii) one or more forbidden TAIs for a list of “forbidden tracking areas for regional provision of service” IE.

Abstract: Solutions pertaining to public land mobile network (PLMN) selection in international areas when a user equipment (UE) supports non-terrestrial network (NTN) communications are proposed. An apparatus implemented in a UE transmits a message indicating that the UE has a capability of NTN communication over a satellite access. The apparatus also receives an indication indicating whether the UE is allowed to utilize one or more NTNs over the satellite access. The apparatus then performs a PLMN selection in a country area or in an international area based on the capability.

Abstract: Examples pertaining to handling of reject causes and forbidden tracking area identifier (TAI) lists in reject messages in mobile communications are described. A user equipment (UE) receives a reject message from a satellite-accessing cell of a network. The UE then stores one or more TAIs that are included in at least one information element (IE) of the reject message in a list of forbidden tracking areas in the UE regardless of a reject cause indicated in the reject message.

Abstract: A method of access domain preference selection for mobile originating short message service (MO SMS) using Attention (AT) command in EPS/5GS is provided. A new AT command is defined to specify the preferred access domain for UE to use for MO SMS over NAS messages when the UE supports non-3GPP access (e.g., in 5GS) and 3GPP access (e.g., in EPS/5GS). The set AT command (+CADSMS=[<access domain preference>]) is provided for the purpose of specify the access preference that the UE will use to send MO SMS over NAS message, the read AT command (+CADSMS?) returns the currently selected access preference, and a test AT command (+CADSMS=?) returns the supported access preference as a compound value.

Abstract: A method of periodically attempting to access the HPLMN or an EHPLMN with higher priority in NTN systems with discontinuous coverage is proposed. A UE registered in VPLMN starts a timer T to periodically attempt to obtain service on its HPLMN or EHPLMN. When access stratum is deactivated due to discontinuous coverage in NTN, the UE does not stop the timer T, and postpone the periodic attempts to a later time, e.g., upon or after the UE activates the access stratum.

Abstract: Examples pertaining to selection of a tracking area identifier (TAI) as a last visited registered TAI in a geographical location in mobile communications are described. A user equipment (UE) receives broadcast information from a network indicating a plurality of tracking area codes (TACs) for the network. The UE then determines one or more candidate TACs, including at least a first TAC, best representing a current geographical location of the UE from the plurality of TACs received by removing zero, one or more TACs of the plurality of TACs from consideration based on the broadcast information received over time.

Abstract: Examples pertaining to selection of a current tracking area identifier (TAI) among multiple current TAIs in non-terrestrial network (NTN) communications are described. A user equipment (UE) initiates a procedure in a satellite-accessing cell of a selected public land mobile network (PLMN). The UE selects a tracking area code (TAC) from a plurality of TACs of the selected PLMN broadcast by the cell as a current TAC such that a tracking area identifier (TAI), constructed from the current TAC and a PLMN identifier (PLMN ID) of the selected PLMN, is a current TAI associated with a geographical area in which the UE is located.

Abstract: Examples pertaining to handling of multiple tracking area identifiers (TAIs) in satellite access in mobile communications are described. A user equipment (UE) initiates a procedure with a satellite-accessing cell of a network. The UE constructs a TAI or a plurality of TAIs, as a list of TAIs, of the cell depending on whether the broadcasts one or more than one tracking area codes (TACs) per public land mobile network (PLMN). The UE receives either a reject message or an accept message from the network responsive to initiating the procedure.

Abstract: Methods and apparatus are provided for EPS fallback status report by the modem to the upper layers. In one embodiment, the mobile terminal (MT) initiates a 5G voice call, detects an EPSFB triggered by the wireless network, identifies one or more EPSFB status and sends one or more EPSFB status indicators to at least one upper layer based on the identified one or more EPSFB status. In one embodiment, the EPS fall back is a redirection procedure. In another embodiment, the EPS fallback is a handover procedure. In yet another embodiment, the one or more EPSFB status indictors comprising a redirection to EPS started indicator, a handover to EPS started indicator, a redirection to EPS failed indicator, a handover to EPS failed indicator, a redirection to EPS success indicator, and a handover to EPS success indicator. In one embodiment, the MT sends EPSFB status indicators using AT command.

Abstract: Methods and apparatus are provided for EPS fallback status report by the modem to the upper layers. In one embodiment, the mobile terminal (MT) initiates a 5G voice call, detects an EPSFB triggered by the wireless network, identifies one or more EPSFB status and sends one or more EPSFB status indicators to at least one upper layer based on the identified one or more EPSFB status. In one embodiment, the EPS fall back is a redirection procedure. In another embodiment, the EPS fallback is a handover procedure. In yet another embodiment, the one or more EPSFB status indictors comprising a redirection to EPS started indicator, a handover to EPS started indicator, a redirection to EPS failed indicator, a handover to EPS failed indicator, a redirection to EPS success indicator, and a handover to EPS success indicator. In one embodiment, the MT sends EPSFB status indicators using AT command.

Abstract: Examples pertaining to protocol improvement for redirection to another system in mobile communications are described. An apparatus in a 5th Generation System (5GS) receives, from a mobile network, a reject cause indicating that redirection to an Evolved Packet System (EPS) is required. Responsive to receiving the reject cause while no suitable cell of the first mobile network connected to an Evolved Packet Core (EPC) is found or while no cell of the first mobile network connected to an EPC can be selected, the apparatus enters a predefined 5th Generation Mobility Management (5GMM) state and starts a timer.

Abstract: A User Equipment (UE) including a wireless transceiver and a controller is provided. The wireless transceiver performs wireless transmission and reception. The controller selects a PLMN via the wireless transceiver, and determines whether a predetermined ciphering algorithm is adopted for a Non-Access Stratum (NAS) security context. In response to selecting the PLMN and the predetermined ciphering algorithm being adopted for the NAS security context, the controller sends an initial NAS message in which Information Elements (IEs) are in cleartext only to the selected PLMN via the wireless transceiver.

Abstract: A method executed by a UE communicatively connected to a first 3rd Generation Partnership Project (3GPP) network utilizing an advanced Radio Access Technology (RAT) is provided. The methods includes the following steps: receiving a message from the first 3GPP network, which indicates that the first 3GPP network supports IP Multimedia Subsystem (IMS) voice over Packet Switched (PS) sessions; and providing an indication that fallback of the UE to a second 3GPP network utilizing a legacy RAT is disabled to the first 3GPP network in response to the receiving of the message.

Abstract: A method for a User Equipment (UE) to enhance Voice Domain Management (VDM) for IP Multimedia Subsystem (IMS) voice provided over a 5G network is provided. The UE receives an indication that causes it to not disable the Evolved-Universal Terrestrial Radio Access (E-UTRA) capability for a Public Land Mobile Network (PLMN), before or after selecting a Next Generation-Radio Access Network (NG-RAN) cell in the PLMN with the UE's usage setting being set to voice centric. The UE enables the E-UTRA capability or keeps the E-UTRA capability enabled in response to the indication.

Abstract: A method executed by a User Equipment (UE) for emergency call handling during a de-registration or detach procedure is provided. The UE initiates a Mobility Management (MM) de-registration procedure or an MM detach procedure with a mobile communication network. The UE initiates an emergency service before the MM de-registration procedure or the MM detach procedure has been completed. In response to the initiation of the emergency call, the UE aborts the MM de-registration procedure or the MM detach procedure and performs local de-registration or local detach. After the local de-registration or the local detach, the UE initiates a registration procedure or an attach procedure.