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220-1201 Practice Question: A customer complains that their VoIP phone…
A customer complains that their VoIP phone intermittently drops calls and has poor audio quality. The phone is connected to a switch port that also carries data traffic for a nearby workstation. What is the most likely cause?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Quality of Service (QoS) is not configured on the switch port.
VoIP is sensitive to latency and packet loss. When a switch port carries both voice and data without proper QoS, data traffic can congest the link, causing dropped packets and poor audio. QoS prioritizes voice traffic to prevent this.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The switch port is set to half-duplex.
Why it's wrong here
Setting a switch port to half-duplex forces devices to take turns sending and receiving data, which significantly increases the likelihood of collisions and retransmissions, especially under moderate to heavy network traffic. While this certainly degrades performance, it typically manifests as consistent slowness or frequent, predictable drops during active use, rather than purely intermittent call drops that fluctuate with network congestion levels.
- ✗
The network cable is too long.
Why it's wrong here
Exceeding the maximum recommended length for a network cable (e.g., 100 meters for standard Ethernet) causes significant signal attenuation and increased susceptibility to electromagnetic interference. This usually results in persistent and severe connectivity issues, such as a complete loss of link, extremely high error rates, or constant packet loss, rather than sporadic and intermittent call drops that are more indicative of fluctuating network resource contention.
- ✓
Quality of Service (QoS) is not configured on the switch port.
Why this is correct
VoIP traffic is highly sensitive to latency, jitter, and packet loss due to its real-time nature. Without Quality of Service (QoS) configured on the switch port, the network treats all data traffic equally. This means that general data transfers or other network activities can easily consume available bandwidth, causing time-sensitive VoIP packets to be delayed, reordered, or dropped, leading directly to intermittent call quality degradation and dropped calls as network load fluctuates.
- ✗
The phone’s firmware is outdated.
Why it's wrong here
While outdated firmware can introduce various bugs, security vulnerabilities, or compatibility issues within a VoIP phone, it is less likely to be the direct cause of intermittent call drops that correlate with network congestion. Firmware-related problems typically manifest as consistent malfunctions, unexpected reboots, or specific feature failures, rather than performance degradation that varies dynamically with the network's overall traffic load, which points more towards a network resource management issue.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 220-1201 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 220-1201 exam.