Techniques for optimizing terminating access domain selection (TADS) flow for a Fifth Generation (5G) standalone (SA) capable interworking device with legacy Fourth Generation (4G) voice over long term evolution (VoLTE) network are discussed herein. A 5G SA capable user equipment (UE) may receive a voice call from any generation network. To receive a 5G voice call on an IP Multimedia Subsystem (IMS) network, a terminating UE must be currently connected to a 5G SA network. However, the system has to determine the currently connected radio access technology (RAT) type before establishing a connection; otherwise, attempts to establish a 5G NR connection would result in network call completion errors. The system may configure a home subscriber server to receive a TADS request for the terminating UE and return a TADS status.