CISSP: Certified Information Systems Security Professional

Because each user has a personal, unique PIN, the most effective approach combines a technical enforcement mechanism with sound user practice: deploy phone locking software that enforces PIN usage and lockout/complexity policies, while instructing each user to periodically change their own PIN (since it is personal to them, not something the administrator should be resetting on their behalf). This layered approach—technical control plus user-driven credential rotation—provides stronger protection against unauthorized VoIP phone usage than administrator-driven PIN resets or passive usage tracking via CDR reports alone, which only provide after-the-fact detection rather than prevention.