If cadets are using company phone numbers to make unsolicited calls, and the logs confirm the numbers are not being spoofed, it suggests that the SIP (Session Initiation Protocol) server's security settings might be weak. This could allow unauthorized access or exploitation of the company's telephony services, potentially leading to misuse by unauthorized individuals.
Reference = CompTIA Security+ SY0-701 study materials, especially on SIP security and common vulnerabilities.