SIP Server Security Weaknesses and Unsolicited Calls
Short answer
B The company’s SIP server security settings are weak, allowing unauthorized users to originate calls using valid company numbers.
Question
Key Takeaways
The core concept tested is SIP trunking security; the common trap is assuming that because numbers are not spoofed, the threat must be external or accidental, ignoring internal misconfiguration.
This question examines the risks associated with insecure Session Initiation Protocol (SIP) servers, specifically how weak security settings allow unauthorized use of company phone numbers for unsolicited calls. It establishes that internal logs confirming non-spoofed numbers point to a configuration vulnerability rather than external spoofing or provider errors.
Common mistake: Option D is the most common wrong answer because candidates confuse duplicate number assignment by providers with active call origination, failing to recognize that provider errors do not explain *who* is making the calls or why they appear as valid internal numbers in logs.
Expert Analysis
Why the Answer Is Correct
The correct answer is B because the logs confirm the numbers are not spoofed, meaning the calls originated from within the organization's own infrastructure. If the SIP server has weak security settings (e.g., lack of authentication, open ports, or default credentials), attackers or malicious insiders can exploit these vulnerabilities to place outbound calls using the company’s legitimate identity. This results in unsolicited calls that appear authentic because they use real, non-spoofed company numbers.
Why the Other Options Are Wrong
Option A is unlikely because executives traveling internationally would typically have a reason for calling partners, but "unsolicited" implies an unwanted or malicious nature, not just cost avoidance. Option C is plausible but less specific than B; while disgruntled employees could make such calls, the question highlights a security analyst validating logs, pointing toward a systemic technical vulnerability (weak SIP settings) rather than a specific human motive. Option D is incorrect because if the service provider assigned duplicate numbers, the receiving end might see confusion, but it doesn't explain how foreign language speakers are actively placing calls through the company's system without authorization.
Community Comment Notes
Community members generally agree on B, noting that weak SIP security allows unauthorized callers to use company numbers. One commenter emphasized that internal logs would not reveal provider-assigned duplicate numbers (D), reinforcing why B is the better technical explanation. Another user noted that checking SIP server security is the immediate next step for the analyst.
Exam Strategy
When analyzing VoIP incidents, always distinguish between spoofed traffic (external forgery) and authorized-origin traffic (internal compromise). If logs show valid, non-spoofed numbers being used maliciously, look first for internal configuration weaknesses like open SIP trunks or missing authentication mechanisms.
Frequently Asked Questions
Why isn't D the answer if numbers are duplicated?
How do we know it's not disgruntled employees?
Community Votes
67% of anonymous learners picked answer B. Votes are pick records left by other test-takers — they are not the verified answer.
Discussion 6 contributions
Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.
From public community threads 6
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johnabayot 👍 3 Answered BThe company's SIP server security settings are weak. This can allow unauthorize callers to use the company's phone numbers to make unsolicited phone calls to the partner organization, or to intercept or modify the SIP messages. Therefore, the security analyst should check the SIP server security settings and make sure they are up to date and follow the best practices for SIP secuirty.
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7308365 👍 2B. Because when a company's SIP server security settings are weak, your phone system can be used to make expensive calls, or for this question specifically, unsolicited phone calls to a partner organization.
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LuckyAro 👍 2 Answered DMultiple companies are using the same numbers
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SecNoob27639 👍 1 Answered BThe security analyst was able to confirm that the numbers weren't spoofed through the phone system logs. If the numbers had simply been duplicated, the security analyst wouldn't have been able to find that info on their internal phone system logs. Even if the service provider had given out duplicate phone numbers as D suggests, it would have looked like a spoofed number to the analyst, as the analyst can only see what is internal to the company. Which is why SIP server vulnerability, not Duplicated phone numbers.
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Hs1208 👍 1 Answered DD. The service provider has assigned multiple companies the same numbers.
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DrCo6991 👍 2 Answered BI believe B is correct.
Reader comments & corrections
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