A user equipment in a communication system, a unified subscription identifier data structure is constructed. The unified subscription identifier data structure includes a plurality of fields that specify information for a selected one of two or more subscription identifier types and selectable parameters associated with the selected subscription identifier type, and wherein the information in the unified subscription identifier data structure is useable by the user equipment to access one or more networks associated with the communication system based on an authentication scenario corresponding to the selected subscription identifier type. For example, during different authentication scenarios, the user equipment utilizes the unified subscription identifier data structure to provide the appropriate subscription identifier (e.g., SUPI, SUCI or IMSI) and associated parameters for a given authentication scenario.