Why QoS Settings Matter More Than You Think for VoIP Call Quality

If you’ve ever heard choppy audio, call drops, delays, or robotic voices, there’s a good chance the issue isn’t your VoIP provider at all.

It’s your network.

More specifically: Quality of Service (QoS).

What Is QoS (and Why VoIP Depends on It)?

QoS is a set of network rules that prioritizes real-time traffic—like voice and video—over less time-sensitive data such as file downloads, backups, or software updates.

VoIP traffic is extremely sensitive to:

• Latency (delay)

• Jitter (packet timing variance)

• Packet loss

Without QoS, voice packets compete with everything else on your network. When congestion hits, calls suffer first.

Why “Good Internet” Isn’t Enough

This is a common misconception:

“We have fast fiber—QoS shouldn’t matter.”

Speed helps, but congestion happens inside your network, not just on your ISP link.

Common culprits include:

• Large file transfers

• Cloud backups

• Video meetings

• Guest Wi-Fi usage

• Security scans and patching

Without QoS, voice traffic gets stuck in line behind all of it.

How to Check If QoS Is Actually Configured

Many organizations think QoS is enabled—but it often isn’t fully implemented end to end.

Here’s how to sanity-check your environment:

1. Check Your Firewall or Router Look for QoS policies, traffic shaping, or DSCP-based rules. If voice traffic isn’t explicitly defined, it’s likely not protected.

2. Verify DSCP Markings Most VoIP platforms mark voice traffic with DSCP EF (46). Those markings must be trusted and preserved across the network.

3. Review Switch Configuration QoS must extend beyond the edge device—access switches, PoE ports, and uplinks all matter. Phones should be on voice VLANs with DSCP trust enabled.

4. Test During Peak Usage If call quality degrades during backups, large file transfers, or company-wide meetings, QoS isn’t doing its job.

Common Signs QoS Is Missing or Misconfigured

• Calls are fine “most of the time”

• Issues appear during busy hours

• Problems feel random or inconsistent

• Reboots temporarily improve quality

These are classic QoS red flags.

QoS Is a Business Continuity Issue, Not Just a Network Setting

Poor call quality impacts:

• Customer experience

• Sales conversations

• Support teams

• Leadership confidence in the phone system

QoS isn’t about perfection—it’s about predictable, reliable communication.

Final Thought

If your VoIP platform is solid but call quality still isn’t consistent, the answer is often inside your own network.

At Interlink, we see this every day. A quick QoS and network readiness review—paired with a properly managed VoIP platform—can eliminate many of the issues organizations struggle with for months.

If you’re unsure whether your network is prioritizing voice correctly, it may be worth a second look.