In VoIP environments — especially those operating at scale or with mission-critical voice traffic — having reliable infrastructure is not enough. The difference between a smooth customer interaction and a frustrating experience lies in how well technical data is interpreted.
Among the many metrics used in voice operations, three indicators stand out for their ability to reflect call quality and guide decisions: MOS, ASR and NER.
When analyzed together, they go far beyond diagnostics. They provide operational insight, guide routing adjustments, help identify network failures, and ultimately protect the user’s experience.
MOS: what the network delivers and what the customer perceives
Mean Opinion Score (MOS) measures perceived voice quality on a scale from 1 (poor) to 5 (excellent). It’s based on latency, jitter, packet loss, and overall network performance. In other words, MOS reflects how the audio sounds to the end user — not just whether the call completed.
Modern tools calculate MOS using perceptual algorithms. However, the score itself must be read in context. A value below 3.5 indicates degraded voice quality, even when the call was technically successful.
That’s why the most effective teams don’t just track MOS as a raw number. They correlate it with time of day, route quality, operators and even campaign types. This makes it possible to detect underperforming routes or infrastructure issues that silently impact customer satisfaction.
ASR: a simple-looking metric with deep operational value
Answer Seizure Ratio (ASR) reflects how many calls were answered out of the total attempted. Although it may seem straightforward, interpreting ASR without context often leads to poor decisions.
For example, outbound campaigns naturally have lower ASR, especially when calling invalid or unavailable numbers. However, sharp ASR drops during specific hours or when using certain carriers often indicate SIP signaling failures, route misconfigurations or authentication issues.
Used strategically, ASR can reveal which routes are efficient, where redial policies need adjustment, and how to improve resource utilization in high-volume environments.
NER: understanding network effectiveness beyond response
Network Effectiveness Ratio (NER) measures the portion of calls successfully delivered to the destination network, regardless of whether someone answered. It focuses on signaling integrity and delivery — not on user behavior.
NER becomes especially valuable when compared to ASR. A high NER with a low ASR suggests the network worked as expected, but recipients didn’t pick up. That can indicate problems with contact strategy, dialing schedules or even the contact base itself — not necessarily technical failure.
This distinction avoids rushed troubleshooting, prevents unnecessary carrier changes and reinforces the value of analyzing technical signals together rather than in isolation.
Technical visibility is what enables true improvement
Treating MOS, ASR and NER as simple numbers on a report hides their full potential. When seen as live signals of voice performance, they offer direction, anticipation and context. This allows engineering teams to act quickly and with clarity — instead of relying on guesswork or trial and error.
Solutions like Insight!, integrated with the Khomp Cloud, deliver this level of visibility. These tools go beyond passive monitoring: they correlate indicators, surface real-time alerts and show teams exactly where and when to act.
When operations teams use trusted metrics, cross-analyze data points and proactively optimize routes or campaign timing, they gain a new level of operational control. And that translates directly into better customer experience, reduced costs and scalable voice infrastructure.