Call Quality Troubleshooting: A Step-by-Step Guide

Diagnosing voice issues in a modern contact center isn’t simple. It could be the SIP trunk. Or the carrier. Or the IVR. Or a misconfigured headset on a remote agent’s laptop.

If you’re a Telecom Lead managing a global voice network, you’ve likely seen it all, and then some. But solving these issues shouldn’t rely on guesswork.

This call quality troubleshooting guide is built for technical teams who live in dashboards and logs and rely on consistent voice quality monitoring to keep call performance in check.. It gives you a repeatable, step-by-step checklist to diagnose and resolve VoIP call quality issues quickly, without playing the blame game.

When Call Quality Fails: What to Look For First

Before diving into packet captures or logs, recognize the symptoms. Most call quality complaints fall into a few categories: choppy or robotic audio, one-way audio, dropped calls or dead air, echo or delay, and IVR navigation failures or distorted prompts. These symptoms can originate anywhere along the call path, from the agent’s device to the final SIP hop. That’s why structured troubleshooting is essential.

The Call Quality Troubleshooting Checklist (Step-by-Step)

Step 1: Isolate the Scope of the Issue

The first step is to isolate the scope of the issue. You need to determine whether the issue affects a single user or multiple users, whether it involves internal extensions or external PSTN calls, and whether it’s limited to one region or spans across countries. Narrowing the scope helps rule out large parts of your infrastructure and immediately points you toward a smaller set of potential causes.

Step 2: Replicate the Problem with Test Calls

Next, replicate the problem with controlled test calls. Manual attempts can work, but automated test calls offer consistency and eliminate human variability. Platforms like Klearcom Connect allow you to simulate real customer calls across geographies and carriers, capturing MOS scores, transcription accuracy, and IVR interaction success. With this approach, you can determine if the problem is intermittent or region-specific and test repeatedly under identical conditions.

Step 3: Review Network Performance Metrics

After replicating the issue, turn to network performance metrics. This means reviewing Mean Opinion Scores (MOS), jitter, latency, and packet loss. For example, MOS below 3.5 usually means poor audio quality. Jitter above 30 milliseconds can result in broken speech, and even 1% packet loss may distort calls. Monitoring tools should help you correlate voice symptoms with these metrics to locate network problems.

Step 4: Check Carrier Routing and Status

The next focus is on your carriers. Sometimes the issue is beyond your network, such as upstream with telephony providers or routing anomalies. Investigate your SIP trunks, PRI circuits, or cloud telephony provider for regional routing problems or degraded paths. Use alternate routes if possible, and verify with carrier dashboards or status pages. Carrier-specific test calls, especially across different geographies, are extremely helpful in identifying if the issue is localized.

Step 5: Analyze IVR/ACD Logs

Now look at your IVR and ACD logs. Check whether prompts played correctly, DTMF inputs were recognized, and call transfers succeeded. Even minor scripting issues can cause dropped calls at specific IVR steps. Contact center systems can reveal if calls got stuck in queues, disconnected abruptly, or failed to play prompts.

Step 6: Validate Endpoint Setup (Agent Devices, Softphones)

Then, validate the agent endpoint setup. Codec mismatches, failing headsets, Wi-Fi connections, or VPN-induced latency can all be culprits. Particularly in hybrid or remote setups, use tools like Klearcom End Station Testing to replicate and verify call behavior from the agent’s local environment.

Step 7: Document and Escalate with Diagnostics

Once you've gathered evidence, document and escalate with diagnostics. Include timestamps, affected numbers, call recordings, MOS history, error logs, and any related SIP messages. This helps your vendors or upstream providers quickly identify the root cause without the usual finger-pointing.

Tips for Troubleshooting at Scale

Manual testing doesn’t scale when you have a global footprint. Always-on tools like Klearcom Connect can simulate test calls continuously from various regions and carriers. Real-time alerts flag issues immediately, while logging and diagnostics provide traceability. These capabilities are essential for proactive monitoring and help you shift from reactive triage to preventive quality control.

Downloadable Version or Internal Use

This checklist shouldn’t be saved for emergencies. Make it a recurring QA tool. Integrate it into your processes during carrier onboarding, network updates, and IVR deployments. It’s also a useful framework for training support staff on voice troubleshooting basics.

Keep Calls Clear and Customers Happy

Structured call quality troubleshooting turns chaos into clarity. It speeds up resolution, improves customer experience, and reduces time lost chasing false leads. In an environment where every failed call erodes trust, proactive monitoring is the new standard. With global numbers to manage, a dependable testing platform like Klearcom gives you the visibility and control you need to keep your voice infrastructure strong.