Supporting SIM toolkit applications in embedded UICCs

Disclosed herein is a technique for enabling Subscriber Identity Module (SIM) toolkit commands to be properly routed within a mobile device that includes an embedded Universal Integrated Circuit Card (eUICC) configured to manage two or more electronic SIMs (eSIMs). Specifically, the technique involves a baseband component of the mobile device and the eUICC initially exchanging information about their eSIM capabilities to identify whether multiple eSIMs are active within the eUICC. During this exchange of information, the eUICC can generate a list of unique identifiers of the active eSIMs that are managed by the eUICC and provide the list of unique identifiers to the baseband component. In turn, the baseband component can update a configuration to manage the list of unique identifiers and use the list of unique identifiers to properly route SIM toolkit commands to the appropriate eSIM within the eUICC.