Imagine you are the network engineer responsible for the Remote Access Domain in your organization. One day, you receive a report that some unauthorized phone numbers have been making calls through your company's VolP phone system, resulting in excessive charges. What action should you take to address this situation? A) Immediately block the identified phone numbers. B) Upgrade the VolP phone system to a more secure version. C) Ignore the report since it might be a false alarm. D) Request assistance from the IT security director to investigate the issue