Apple patents method for phones to pick best network slices while roaming

1. One or more non-transitory, computer-readable media having instructions that, when executed, cause processor circuitry to: generate, for transmission to a first access and mobility management function (AMF) of a first visited public land mobile network (VPLMN), a first registration request message that includes a requested network slice selection assistance information (NSSAI) and a network slice steering of roaming (NSSoR) indication to request an NSSoR update; receive, in response to the registration request message, a registration accept message that includes an NSSoR container with information that indicates a second VPLMN supports one or more network slices, wherein the information of the NSSOR container comprises priority and slice-support information for a plurality of VPLMNs; store the priority and slice-support information in a local VPLMN priority slice selection database; initiate an application or service that is mapped to a first slice; access the local VPLMN priority slice selection database to determine the one or more network slices supported by the second VPLMN include the first slice; and generate a second registration request message for transmission to a second AMF of the second VPLMN based on the one or more network slices including the first slice.