How to troubleshoot and fix Wi-Fi calling or VoIP call quality issues on your business network

Summary

This guide helps you troubleshoot and resolve: How to troubleshoot and fix Wi-Fi calling or VoIP call quality issues on your business network. Follow the steps below to fix the issue.

Common Causes

Wi-Fi calling and VoIP services like Microsoft Teams, Zoom, and 3CX rely on a stable network connection to deliver clear audio and reliable call performance. When your office network struggles with congestion, interference, or misconfiguration, you'll often notice the symptoms first during voice calls: choppy audio, robotic-sounding voices, echo, dropped calls, or one-way audio. This guide walks you through diagnosing and resolving these issues on your business network, starting with the quickest fixes and moving into more detailed troubleshooting.

Quick Fix Steps

Before diving into detailed diagnostics, work through these quick checks. They resolve the majority of call quality issues we see across our customer base.

1. Restart your network equipment. Power off your modem and router, wait 30 seconds, then power them back on. Wait a further two minutes for the connection to fully re-establish before testing a call.
2. Move closer to your access point. Wi-Fi signal strength drops significantly through walls, floors, and metal objects. If the issue only happens in certain rooms, distance or interference is likely the cause.
3. Switch to a wired connection. If your device has an Ethernet port, plug it directly into your router or switch for the most reliable voice quality.
4. Close bandwidth-heavy applications. Pause large file downloads, cloud backups, video streaming, and other video conferencing sessions on the same network while testing.
5. Test on a different device. Try the same VoIP app on a mobile device using mobile data. If the call is clear, the problem is isolated to your office network or device.

Detailed Troubleshooting

If the quick fixes didn't resolve the issue, work through the following sections in order. Each step builds on the previous one and helps narrow down the root cause.

Check Your Internet Service Health

Voice calls require consistent upload and download speeds with low latency. Even a fast connection can produce poor call quality if it's unstable.

1. Connect a computer directly to your modem via Ethernet, bypassing your router. Note: this will temporarily disconnect other users from the network.
2. Run a speed test at speedtest.net and record your results.
3. Run the test three times, spaced two minutes apart, to check for consistency.
4. Compare your results against the requirements of your VoIP service:
   • Microsoft Teams: 1.2 Mbps up / 1.2 Mbps down per call (HD), 4 Mbps up / 4 Mbps down for HD video
   • Zoom: 1.5 Mbps up / 1.5 Mbps down for HD voice and video
   • 3CX: 1 Mbps up / 1 Mbps down per concurrent call
5. Check your latency (ping) — anything above 100 ms will cause noticeable audio delays.

If your speeds are well below your plan's advertised rates, or if results vary wildly between tests, there may be an issue with your internet service. Open a Ticket and we'll investigate.

Optimise Your Wi-Fi Network for Voice Traffic

Wi-Fi is convenient but inherently less stable than wired connections. For business-grade call quality, you need to tune your wireless network specifically for voice traffic.

Separate Voice and Data Traffic

If your router supports VLANs or multiple SSIDs, create a dedicated network for voice devices and conferencing hardware. This prevents large file transfers or video streaming from competing with your call traffic.

Use the 5 GHz Band

The 5 GHz band offers faster speeds and less interference than 2.4 GHz, though it has a shorter range. For voice devices that stay relatively close to your access point, 5 GHz is the better choice.

1. Access your router's admin panel (typically 192.168.0.1 or 192.168.1.1 in a browser).
2. Navigate to the Wireless Settings section.
3. Confirm both 2.4 GHz and 5 GHz networks are enabled with distinct SSIDs.
4. Connect your voice devices to the 5 GHz SSID.

Reduce Wi-Fi Interference

Common sources of interference include microwave ovens, Bluetooth devices, neighbouring Wi-Fi networks, and older cordless phones. Position your access points away from these sources and, where possible, mount them high on walls or ceilings.

Configure Quality of Service (QoS) Settings

QoS is the most effective tool for prioritising voice traffic on your network. When configured correctly, it ensures your VoIP calls always get the bandwidth they need, even when the network is busy.

1. Log into your router's admin panel.
2. Locate the QoS or Traffic Management section (often under Advanced Settings).
3. Enable QoS if it isn't already.
4. Add rules to prioritise voice and video conferencing traffic. Most modern routers allow you to prioritise traffic by application category (such as VoIP or video conferencing) rather than by specific ports, which is simpler and more reliable. If your router requires manual port rules, refer to the official documentation from Microsoft, Zoom, or 3CX for the current port ranges, as these change between versions.
5. Set voice traffic rules to High priority and save your changes.

Check Your Device and Application Settings

Sometimes the issue isn't the network at all — it's the device or application configuration.

Microsoft Teams

1. Click the three dots next to your profile picture and select Settings.
2. Go to Audio & video.
3. Under Audio devices, confirm the correct microphone and speaker are selected.
4. Run the Test call under Make a test call to diagnose issues.
5. Disable Noise suppression temporarily to see if it's causing distortion.

Zoom

1. Click your profile picture and select Settings.
2. Click the Audio tab.
3. Run through the Speaker and Microphone test sections.
4. Toggle Suppress background noise to Low or Disable if audio sounds muffled.
5. Check the Video tab and turn off HD video if you're experiencing performance issues.

3CX

1. Open the 3CX web client or desktop app.
2. Click Settings then Audio.
3. Test your microphone and speaker using the built-in diagnostics.
4. Confirm your headset is selected as the default device.

Update Firmware and Software

Outdated firmware on routers and access points can cause compatibility issues with modern VoIP codecs. Similarly, older versions of Teams, Zoom, or 3CX clients may have known bugs that affect call quality.

1. Check your router manufacturer's website for the latest firmware version and compare it to what's installed on your device.
2. Log into your router's admin panel and apply any available firmware updates. Most routers have an automatic update option you can enable.
3. Update your access points in the same way if they are managed separately.
4. Ensure your VoIP applications are running the latest version. Most apps update automatically, but you can force a check from within the settings menu of Teams, Zoom, or 3CX.
5. Restart all devices after updating to ensure changes take effect.

When to Escalate

If you've worked through every section above and call quality is still poor, the issue may lie outside your local network — for example, with your internet service provider, your VoIP provider's infrastructure, or the remote party's connection. At this point, detailed packet captures and provider-side diagnostics are usually required.

Open a Ticket with the results of the tests you've run so far, and our team will work with you and your service providers to isolate the cause.

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