Handling PLMN Prioritization

Abstract

A user equipment (UE) transmits a registration request message to a first public land mobile network (PLMN), wherein the first PLMN is a roaming PLMN, receives a registration accept message from the first PLMN, determines that the registration accept message includes a manipulated steering of roaming (SoR) container or does not include a SoR container, wherein the SoR container is configured by a home PLMN (HPLMN) of the UE and transmitted to the first PLMN from the HPLMN, determines that the registration accept message includes an indication that the first PLMN does not support voice over packet switching (VoPS) and adds the first PLMN to a first list of PLMNs in which voice service is not possible in an N1 mode.

1 - 21 . (canceled) 
     
     
         22 . A base station, comprising:
 a transceiver configured to communicate with a user equipment (UE); and   
       a processor communicatively coupled to the transceiver and configured to perform operations comprising: 
       receiving, from the UE, a registration request message for a first public land mobile network (PLMN), wherein the first PLMN is a roaming PLMN; and 
       transmitting, to the UE, a registration accept message comprising a steering of roaming (SoR) container, wherein the SoR container is configured by a home PLMN (HPLMN) of the UE and transmitted to the first PLMN from the HPLMN, wherein the registration accept message further comprises an indication of whether the first PLMN supports voice over packet switching (VoPS). 
     
     
         23 . The base station of  claim 22 , wherein the operations further comprise:
 receiving, from the UE, a registration complete message.   
     
     
         24 . The base station of  claim 22 , wherein the SoR container is a manipulated SoR container. 
     
     
         25 . The base station of  claim 22 , wherein the SoR container is an unmanipulated SoR container. 
     
     
         26 . The base station of  claim 25 , wherein the first PLMN supports VoPS. 
     
     
         27 . The base station of  claim 26 , wherein based on the unmanipulated SoR container and the first PLMN support of the VoPS, the UE camps on the base station. 
     
     
         28 . The base station of  claim 22 , wherein the first PLMN does not support VoPS. 
     
     
         29 . A processor of a base station configured to perform operations comprising:
 receiving, from a user equipment (UE), a registration request message for a first public land mobile network (PLMN), wherein the first PLMN is a roaming PLMN; and   transmitting, to the UE, a registration accept message comprising a steering of roaming (SoR) container, wherein the SoR container is configured by a home PLMN (HPLMN) of the UE and transmitted to the first PLMN from the HPLMN, wherein the registration accept message further comprises an indication of whether the first PLMN supports voice over packet switching (VoPS).   
     
     
         30 . The processor of  claim 29 , wherein the operations further comprise:
 receiving, from the UE, a registration complete message.   
     
     
         31 . The processor of  claim 29 , wherein the SoR container is a manipulated SoR container. 
     
     
         32 . The processor of  claim 29 , wherein the SoR container is an unmanipulated SoR container. 
     
     
         33 . The processor of  claim 32 , wherein the first PLMN supports VoPS. 
     
     
         34 . The processor of  claim 33 , wherein based on the unmanipulated SoR container and the first PLMN support of the VoPS, the UE camps on the base station. 
     
     
         35 . The processor of  claim 29 , wherein the first PLMN does not support VoPS. 
     
     
         36 . A method performed by a base station, comprising:
 receiving, from a user equipment (UE), a registration request message for a first public land mobile network (PLMN), wherein the first PLMN is a roaming PLMN; and   transmitting, to the UE, a registration accept message comprising a steering of roaming (SoR) container, wherein the SoR container is configured by a home PLMN (HPLMN) of the UE and transmitted to the first PLMN from the HPLMN, wherein the registration accept message further comprises an indication of whether the first PLMN supports voice over packet switching (VoPS).   
     
     
         37 . The method of  claim 36 , further comprising:
 receiving, from the UE, a registration complete message.   
     
     
         38 . The method of  claim 36 , wherein the SoR container is a manipulated SoR container. 
     
     
         39 . The method of  claim 36 , wherein the SoR container is an unmanipulated SoR container. 
     
     
         40 . The method of  claim 39 , wherein the first PLMN supports VoPS. 
     
     
         41 . The method of  claim 40 , wherein based on the unmanipulated SoR container and the first PLMN support of the VoPS, the UE camps on the base station.