220-1101 Question 449
Single answerPoor Voice over Internet Protocol (VoIP) qualityA small office recently moved its IP phones and user PCs onto the same Ethernet switches. Since the change, employees report choppy audio and brief call dropouts on VoIP calls, especially when large files are being copied across the network. Internet access is otherwise working. Which action is the BEST first step to improve VoIP call quality?
- A
Enable Quality of Service (QoS) to prioritize voice traffic on the network
- B
Increase the screen resolution on the users' PCs to reduce bandwidth usage
- C
Replace all IP phones because intermittent audio indicates failing phone hardware
- D
Disable DHCP and assign static IP addresses to every phone and workstation
Show answer and explanation
Correct answer: A
Explanation
The key clue is that VoIP quality degrades when large files are transferred after phones and PCs began sharing the same switching infrastructure. In real deployments, voice traffic should be prioritized because VoIP depends on low latency, low jitter, and minimal packet loss. QoS is a common and appropriate first troubleshooting step in this situation. Best practices from network and VoIP vendors commonly recommend prioritizing RTP/voice traffic and, where supported, using voice VLANs and QoS policies on switches and routers. The other options do not address the symptoms or root cause: display settings do not affect packet prioritization, widespread simultaneous phone failure is unlikely, and static IP addressing does not solve congestion-related voice quality problems.
- A. Correct.
Correct. VoIP is highly sensitive to latency, jitter, and packet loss. When voice and data share the same switches and links, large file transfers can compete with voice packets. Enabling QoS and prioritizing voice traffic is a standard best practice to reduce delay and jitter and improve call quality during congestion.
- B. Incorrect.
Incorrect. Screen resolution has no meaningful relationship to Ethernet bandwidth consumption for normal desktop use in this scenario. This option reflects a misunderstanding between local display settings and network traffic affecting VoIP performance.
- C. Incorrect.
Incorrect. Although faulty phones can cause isolated audio issues, the problem appears across multiple users and occurs specifically during heavy data transfers. That pattern points to network congestion or traffic prioritization problems, not simultaneous hardware failure of all phones.
- D. Incorrect.
Incorrect. Static addressing does not address the root cause of choppy audio during periods of high network utilization. DHCP can be used successfully in VoIP environments, and replacing it with static IPs would add administrative overhead without fixing latency, jitter, or packet prioritization issues.