Using virtualized network management functions, the Service Based Architecture will replace the Reference Point Architecture for managing future mobile networks. It naturally lacks a clear security perimeter and has an increased attack surface, so defending the control plane against attacks requires a novel protection paradigm. Both National Institute of Standards and Technology and 3rd Generation Partnership Project suggest moving from perimeter security to a Zero Trust Architecture (ZTA), authenticating all request initiators and controlling access to all resources for each request. However, it insofar remains somewhat unclear to which extent the suggested management protocols do indeed meet the ZTA. We are exploring the standardized communication management protocols in this paper. Our analysis indicates that with careful implementation, the existing network functions and protocols can indeed achieve comprehensive authentication and access control so that the ZTA can be met.