How to troubleshoot call quality issues on VoIP systems

If you’re experiencing poor VoIP call quality (choppy audio, dropped calls, or scrambled sound), the most common culprit is an "unstable network", especially when it involves jitter, high ping, or bandwidth congestion. 

Running a speed test and checking jitter/ping values is the fastest way to get to the root of the problem.

    Please note: VoIP performance depends heavily on your internet connection stability.

Causes of Call Quality Issues

Here are the main factors that affect VoIP performance:

• Jitter: packets arrive out of order, causing distorted audio. Anything above 30ms can cause problems.
• Ping (latency): delays in packet delivery. Anything above 20ms may disrupt calls.
• Bandwidth congestion: too many devices or heavy downloads competing for bandwidth.
• Router settings: features like SIP ALG can interfere with VoIP traffic.
• Network compatibility: some providers may not fully support VoIP.

Troubleshooting Steps

Here are the steps you can take to improve call quality:

• Run a speed test: use Cloudflare Speedtest to check jitter and ping.
• Check jitter: if above 30ms, investigate your connection stability.
• Check ping: if above 20ms, look for network delays or congestion.
• Test different connections: compare WiFi vs. mobile data to isolate the issue.
• Prioritise VoIP traffic: ask your provider to enable QoS (Quality of Service) for VoIP packets.
• Disable SIP ALG: check router settings and turn this off.
• Reduce bandwidth use: disconnect unused devices or pause large downloads.
• Confirm provider support: ensure your ISP supports VoIP traffic properly.

Best Practices

Here are the recommended practices to maintain stable VoIP calls:

• Limit background usage: avoid streaming or large downloads during calls.
• Use wired connections: Ethernet is more stable than WiFi.
• Monitor regularly: run periodic speed tests to catch issues early.
• Contact ISP: if problems persist, ask your provider to review your line and prioritise VoIP.

Related Articles

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• SIP ALG and its impact on VoIP