A technician receives several complaints from the same office about VoIP calls sounding broken up, being difficult to hear, and having lagging audio…

The user complaints describe symptoms of high jitter and latency, which severely impact real-time applications like VoIP. Since the internet speed test is normal, the issue is not a lack of bandwidth but rather network congestion where VoIP packets are not being prioritized. Enabling Quality of Service (QoS) on the router allows a network administrator to classify and prioritize traffic. By giving VoIP packets higher priority than other data (like web browsing or file transfers), QoS ensures they are delivered promptly, reducing jitter and latency and resolving the broken audio issues.

B. Configuring PoE (Power over Ethernet) provides electrical power to devices over network cables but has no impact on data traffic quality or prioritization.

C. Changing Wi-Fi encryption standards (WPA3/WPA2) is a security measure and does not affect packet latency or jitter for wired or wireless clients.

D. MAC address filtering is a security feature that controls which devices can access the network; it does not manage the quality of traffic for connected devices.

1. Cisco Systems, Inc. (2022). Enterprise Quality of Service (QoS) Solution Design Guide. Chapter: "QoS for Voice." This guide details how QoS mechanisms are essential for classifying and prioritizing voice traffic (VoIP) to guarantee low latency, jitter, and loss, which are critical for acceptable call quality.

2. Kurose, J. F., & Ross, K. W. (2021). Computer Networking: A Top-Down Approach (8th ed.). Pearson. Chapter 6, Section 6.4, "Principles of Congestion Control," and supplementary sections on QoS explain how mechanisms like packet scheduling and classification are used to provide differentiated services for real-time applications like IP telephony.